Since I was an undergraduate student at the School of Architecture, Politecnico di Milano, in the 1990s, the concept of space almost exclusively attracted my attention. I soon learned — from critics and architects — that Architecture was a discipline concerned with space; but it took me a while to understand what that really meant; and it took me even more time to understand that what I believed it was space (what people usually call space, actually), in many circumstances, was place. It also took time to understand that the reduction of place to space has consequences that we easily underestimate. The passage from understanding space and place according to the common sense — that is as unclarified notions —  to understanding space, place, and their relation according to more technical, scientific and, at the same time, more philosophical perspectives was difficult, and it required many types of readings that almost totally absorbed my activity for years. Since my early years at the university, I’ve always been used to take notes, make sketches or drawings on A6-format notebooks, which during the years passed from containing a mix of theoretical and practical observations concerning architecture — which at that time I understood as a discipline of space —, to almost exclusively abstract speculations on the spatial/placial character of reality, of which architecture is an important part, which, like it or not, directly impacts the life of people. By accident, I recently came across a note I wrote years ago, while I was working on the linguistic analysis of space and place; that note was about the concept of place, its linguistic legacy and historico-philosophical meaning. The overall argument — Limit, Place, Appearance — is well-know: it goes back to Aristotle’s definition of place (topos), which is based on the notion of limit – place (topos) is ‘the first unchangeable limit (peras) of that which surrounds.’
That is what place (topos) is: the first unchangeable limit (peras) of that which surroundsARISTOTLE
The same argument often resurfaced in the philosophy of Heidegger who, in the text ‘Parmenides’, affirms that ‘the limit (πέρας), as thought by the Greeks, is, however, not that at which something stops, but that in which something originates, precisely by originating therein as being “formed” in this or that way, i.e., allowed to rest in a form and as such to come into presence. Where demarcation is lacking, nothing can come to presence as that which it is.’
the limit, as thought by the Greeks, is not that at which something stops, but that in which something originatesMARTIN HEIDEGGER
This is precisely the argument of that old note I’ve drawn on for the present article. More recently, the question of limit and place had valid specific recognition by philosophers like Massimo Cacciari, Edward S. Casey, Jeff Malpas and other scholars. I’ve also considered this issue in the article The Τόπος of a Thing. Despite that, it seems to me that the heuristic starting point of my old note was, to my current knowledge, quite personal, that’s why I’m writing about it. In the meanwhile, I have abandoned my old A6-format paper notebooks in favour of more up-to-date digital versions; I lost one spatial dimension, actually — an irremediable loss for the spatial and epistemological abilities of an architect —, but I gained an almost infinite amount of digital space for taking notes, memoranda, and have my past notebooks (which I have digitalized), photos, books, etc. always with me, which is a very good option for those who, like me, appointed their travelling body as the ultimate place of dwelling, or residence.
1. Limit, Place, Appearance
One of the first books that I’ve read when I decided to deepen the relationship between language and the concepts of space and place was The Origin of Language, by the American linguist Merritt Ruhlen. My overall scope was to see what the ultimate linguistic source of meaning available for those spatial concepts could be; therefore, I considered that a history of language, down to Proto-Indo-European sources, was a good option to start with. I had to rely on many lateral or secondary sources to trace back the histories of space and place — in the article Back to the Origins of Space and Place — to find enough literature beyond the canonical succinct argumentation that we find in dictionaries and in those books that deal with spatial questions. I have chosen Ruhlen’s text for a number of reasons: first, it deals with origins, which is an issue I’m instinctively very close to, independently of the discipline; then, it was accessible to non-specialists, which is always a plus for expanding the edge knowledge (which I intend as a collective effort), and for which a clear communication that is able to go beyond specific disciplinary boundaries is the necessary requirement. Finally — very important to me and the spirit of my research —, Ruhlen’s approach was interdisciplinary, or, even better transdisciplinary: his work, as a linguist, can be analysed in close correlation to the work of the Italian geneticist Luigi Luca Cavalli Sforza and the British archaeologist Colin Renfrew, to prove the correlation between language and the common origins of human races and cultures. I believe these are the kind studies and approaches to knowledge that silently contribute to change the vision of an epoch and of human history. One of the evidence concerning Ruhlen’s work on The Origin of Language (reinforced by genetics and archaeological clues) is that ‘all the languages now spoken on earth […] are descendants of a single ancestral language.’ Ruhlen proposes a classification of languages into families which ‘is based on discovering words in different languages that are similar in sound and meaning.’ And it was properly the similarity in sound and meaning between words in different languages that suggested me the following considerations concerning the intimate nexus between place, limit and appearance.
Fundamentally, place is a question of limits: place is that which appears as a consequence of limits; that’s why place is a phenomenon. To tell it straight, there is a striking similarity in sound between the pronounce of the English word ‘appearance’ and the Greek term ‘peras’ (πέρας) which means ‘limit’.
The same holds for the Latin descendant of ‘appearance’, in a form like ‘apparens’ from the verb appareo, which means ‘to be seen physically, be visible… to be noticed, show itself… to appear, show up’. I find quite singular that it is possible to trace a logical as well as an evident linguistic correlation to make a proposition where ‘appearance’ and ‘limit’ are explicative of each other function, thereby revealing their common origin. In fact, only a thing that has a limit can appear as an individual entity, standing out from the multitudes of entities that compose the background-as-stage of that appearance.
The limit — peras — is that which enables an event (or a set of processes) to be gathered within a definite region, so that the limit is the essential condition for that particular region to appear under the guise of a definite entity, like a rock (actualization of physicochemical processes), a tree, an animal (actualization of biological processes), a nation-state (actualization of social processes), a sculpture, a building, or a geometric solid, let’s say an icosahedron (actualization of symbolic or intellectual processes). ‘Appearance’ and ‘limit’ are two different words that have a linguistic affinity (for sound and correlation of meanings — the meaning of one term is contained in, or explicated by the other) through the Greek antecedent term for ‘limit’ — peras; in turn, their commonality is the remainder of a still more fundamental type of processuality hidden behind and expressed by the Proto-Indo-European root *per which means ‘to cross, pass through’. What that processuality is about? For a thing to appear within its limit, it is necessary to pass through a domain of sheer potentiality — an ideal, or abstract domain — into the realm of actuality: this is what ‘to cross’ or ‘to pass through’ means, according to my interpretation. A process is actualized into a concrete entity whenever it passes through or crosses the threshold that divides a potential (or ideal) domain from the actual and concrete realm of facts, things and phenomena: one is the realm or domain where everything is potentially possible; the other is the realm where an ocean of different possibilities ‘decohere’ into a single fact, entity or phenomenon. The appearance of a limit can also be thought of as the proof of the supreme passage that correlates ontological and epistemological levels of explanations concerning reality. The emplacement of an entity within its limits contemporarily unites the entity (which passed through the process of emplacement as a form of actualization) to the subject for which that entity represents the object of appearance, a thing. I believe this passage, which is, at the same time, a moment of separation (discrimen) and union between different domains or realms, is very likely implicated in the realization of Plato’s notion chōra, which is a notion that has a fundamental sieve-like character and function: for me, that sieve-like character is the representation of a threshold (again a question of limits to be traversed) that formalizes the passage from that which is abstract, ideal or potential — that which is intelligible to use Plato’s terminology — into that which is actual and concrete — that which is sensible (I have tried to illustrate that passage in a previous article — see Image 8, Place, Space, and the Fabric of Reality). When certain processes pass through a certain threshold (when they pass the sieve between the potential/intelligible and the actual/sensible) that threshold is reified into a limit within which the thing — entity, fact or phenomenon — concretely appears. The thing is a place: the place of actualized processes. This is also the way I understand the difference between process and reality: processes, just like relations, are intrinsically abstract and we can only find their traces when they actualize into something concrete. This is a recurrent theme for me: processes are concealed to our senses, and the limit through which processes are gathered and actualized within discrete forms-entities (appearance of physicochemical, biological, socio-cultural and symbolic states of place) unveils their concealed presence. At the time I wrote that old note, and even when I started working at the present article, I didn’t know that this kind of interpretation — the limit as a metaphysical origin that separates and unites that which is concealed (processes) to that which is unconcealed (entities as actualization of processes) — could also be a possible way to elucidate Heidegger’s understanding of aletheia — the unconcealment of beings — as described by the Australian philosopher Jeff Malpas. The linguistic necessity to differentiate ‘appearance’ from the ‘limit’ of the thing that appears — or the necessity to create distinct words from one common antecedent term — is a confirmation of the ingrained abstract tendency of the human mind to use language to generate always new meanings to extend the edge of knowledge. Abstraction is a cognitive process. To separate the process of appearance, after which the thing appears (as a concrete entity), from the limit, which is immanent to the thing that appears, means to bifurcate nature.
Here, there are different bifurcations at stake: the first regards the separation between the object/thing and its place (I believe this is the reason why Aristotle — and, with few remarkable exceptions, the philosophers after him — rejected the coincidence between thing and place). The second bifurcation, which is even more fundamental, regards the separation between object and subject: on the one side, there is the subject to whom appearance is referred (the thing appears to the perceiving subject); on the other side, there is the object within its limits. Not to mention the separation between objects themselves. This limit (threshold, boundary, margin, edge, border, etc. these are all different ways of understanding the concept of limit) is more often understood as a moment of abrupt spatial separation — terminus — rather than as a moment of distinction within a more encompassing horizon of placial union, as hypothesized by Heidegger, or, more recently, by Casey, when he speaks of borders, boundaries and the differences they generate in terms of ‘compenetrative presences’, or as it is in the intentions of my reformed notion of place (which I began to develop starting from phenomenological considerations applied to architecture). This fundamental question concerning the ‘withness’ intrinsic to limits is also clearly argued for by the Italian philosopher Massimo Cacciari in the essay Place and Limit, where he says that the limit ‘seems to indicate the “line” along which two domains touch each other: cum-finis. The limit distinguishes, therefore, by combining.‘
the limit (cum-finis) distinguishes by combinigMASSIMO CACCIARI
Therefore, the limit — the limit of a place — cannot be conceived of as a rigid barrier or a border that denies exchanges; rather, it should be understood as a porous boundary, like the membrane of a cell that allows a dynamic balance between inside and outside, a membrane that fundamentally distinguishes (limit as terminus) and combine (limit as cum-finis) two different realities: what is inside and what is outside, terminus and cum-finis, at the same time; this is the ultimate condition for a place to exist and thrive. The very structure of place that I have imagined — characterized by processuality, relationality, emergence, evolutionary and choral values, see the article What Is Place? What Is Space? — goes in this direction of discernment (discrimen) between entities within a unifying horizon. We should be aware that bifurcations, or crystallized separations between subject and object, between object and place (or space, for those who believe space is a concrete entity), or between objects themselves, can develop into fallacies of thinking due to the improper use and understanding of abstraction. Yet, if we remind that what is lost through words (immediacy) can be gained in imagination, communication and knowledge, we can always find the original unity of sense between language and reality, between the intelligible and the sensible, between place and the thing, other than between place and space.
2. Ontologies and Epistemologies of Limit
I stay a little bit more on the ontological and epistemological difference between that which has a limit and appears as a concrete entity — place —, and that which has not a limit and cannot appear — space. As I have said, the concretization of processes within a certain threshold or limit, regards the passage from an unlimited realm, or domain of possibilities, into the limited realm of actual things and facts. Within the former — the limitless — ‘every-thing’ is abstract, ideal or potential; we can imagine this domain, or realm, as a reservoir of infinite possibilities; a potential domain, where Schrödinger’s cat can be dead and alive, at the same time, to mention a popular example that theoretical physicists use to explain the oddities of quantum mechanics. The other realm is the concrete and actual realm where any entity appears within its limits, under the guise of a concrete thing, fact, phenomenon, or place (this is the place of processes gathered within the limit); this is the finite and concrete realm of actuality, where Schrödinger’s cat is definitely dead or alive — the realm where different possibilities, or probabilities, decohere into a finite state (a state of place — physicochemical, biological, social or symbolic state of place).
The limit separates and brings together, by contrast, that which is within the limit and that which is without.
We ought to think this way if we understand reality in terms of interrelated systems and emergence: if only separation existed there could be no emergence at all; in fact, the limit intrinsically connect the ‘in which’ and the ‘out of which’, given that there can be no ‘in which’ (as a kind of standing within) without ‘out of which’ (as a kind of standing out within), or, to put it another way, there can be no inside without outside — the two are reciprocally connected as a condition of distinction within a more encompassing common horizon. The connection between the ‘in which’ and the ‘out of which’ (the substrate necessary to the emergence of the entity) remains active even after the distinction has been actualized through the limit; despite that, this doesn’t mean that what emerges from the substrate is dependent on, or is determined by that substrate. At a metaphysical level, Plato decided to solve this baffling coexistence/exclusion between realms, with the introduction of a mediatory entity or realm — chōra. By saying that place encompasses both concrete and abstract, actual and potential dimensions, I try to follow Plato’s footsteps, by means of the more easy-to-handle concept of place (I mean a reformed concept of place like the one I’m arguing for here, at rethinkingspaceandplace.com): as I often say, place emerges as a concrete entity from the domain of physical processes and extends its encompassing embrace, as abstract entity, in the domain of symbolic or intellectual processes. There is a correlation between the two states of place (physicochemical and symbolic states), which are so far apart but which coexist within the same horizon thanks to the mediating agency of biological and social states (all of the four states are jointly constitutive elements of place understood as encompassing horizon or unit); fundamentally, between physicochemical and symbolic states of place, there is the same type of correlation that exists between the state of sensible and intelligible things.
In antiquity, understanding reality as placial/spatial realm, within or without limits, was often discussed in terms of the contraposition between topos and to kenon (the void); it was the negation of the idea of the void, proposed by the Atomists, that took Aristotle to conceive his plenist physical theory, focused on the concept of place (topos). Concerning this question — the placial/spatial understanding of reality and the metaphysical question of limit — I think it is even more fruitful to consider the contraposition-correlation between the Aristotelian notion of topos and the apeiron of Anaximander. If Aristotle’s topos (place) was defined with respect to the presence of a limit (peras), Anaximander’s apeiron was characterized by the lack of limits, precisely: the ‘a-’ in apeiron stands for negation; therefore, in this case, we are accounting for the negation of limits, peras → a-peiron, that is, that which is ‘limitless’ or ‘unbounded’. No-thing appears — no-thing can appear to our senses — in this domain, where everything is without limits. The reason is obvious: we are bounded entities, therefore, we can only directly account for sensible entities, which are limited by the senses, or by their technological extensions. Despite this intrinsically organic limitation, we can indirectly account for many different kinds of intelligible entities (ideal, abstract, potential things…), which are unlimited entities, that is, entities that are not limited by the senses and which we can apprehend by the seemingly unlimited possibilities of the mind and its abstract cognitive processes (it is interesting to note that such unlimited possibilities emerge from an intrinsically limited territory, as Kant showed with his work, almost totally concerned with setting up the limits of Reason). With respect to those two entities (topos and the apeiron) which are the tokens for two different kinds of realm, the other spatial/placial notion of antiquity — chōra — can be seen as Plato’s creative solution to mediate between them, considered as two extremes far apart; in fact, if we attribute topos the status of that which can be grasped by the senses and the apeiron the status of that which can only be grasped by the intellect, chōra is the entity (term, concept or realm) that mediates between the two. If something that we believed could not appear, for some reason, appears (i.e. a literary unicorn or a hypothetical subatomic particle), then it means that that ‘something’ has passed through the threshold that distinguished the potential/possible from the actual (before its ‘eventual’ appearance, we had no certainties about the real nature of that ‘something’), or the intelligible from the sensible; this passage reifies the impalpable threshold between realms into the limit of the appearance of that ‘something’. However, from that passage, we cannot assume that the apeiron (or any of its possible representations) exists as a concrete entity, but we can only assume that the apeiron (or any of its possible representations) exists as an abstract, potential or ideal entity, realm or domain. We could even assume that the apeiron is a concrete entity — a concrete realm —, but that would be pointless, given that the impossibility to prove its overall reality would reduce it to an abstract idea, returning to where we started: it would just be one of the many possible representations of what Plato called intelligible realm — I have used the concept of apeiron to refer to an unlimited domain opposite-and-correlate to topos, or place, which is the limited and concrete realm. To tell it differently, this means that we can imagine there is truly a real, concrete world ‘out there’ that produces the shadows that we see on the back of the cave (our place); but we can only see those shadows, actually, and just imagine what produced them. Yet, be careful: these shadows are real, they are concrete! They are facts! They are ‘objective’. They are not hallucinations or fantasies. They are parts of the ‘out there’ the same way the real objects that produce those shadows are ‘out there’. They are ‘out there’ the same way we are part of it, ‘here’, flesh and blood. ‘In-here’ and ‘out-there’ coexist through the limit (the limit of our existence); they are mutually related, two complementary parts of a unique entangled environmental system (I have already hinted at this Platonic question concerning the ‘Allegory of the cave‘ in the article Place, Space, and the Fabric of Reality, see Image 2 and note 4, especially). As for the concept of space (I mean the three-dimensional container — the result of symbolic/intellectual processes inquiring into the structure of reality), which has many analogies with the apeiron and the void, but which cannot be identified with them, this is just one of the seemingly infinite intellectual possibilities that belong to the realm of that which has not a limit and cannot be seen.
 I have taken the expression ‘unclarified notion’ from Edward S. Casey, The Fate of Place: A Philosophical History (Berkeley: University of California Press, 1997), xii. About its meaning, see also note  in the article Urban Spaces or Places? While Casey explicitly refers to the concept of place as an unclarified notion, I have extended the compass of that expression to the concept of space, which is a notion everybody makes use of, but whose very meaning is rarely discussed or elucidated; it is almost exclusively taken for granted.
 In Physics (212a 20-21) Aristotle defines place — ‘topos’ in Greek – ‘the innermost motionless boundary of the container’ (W.D. Ross, Aristotle’s Physics. A Revised Text with Introduction and Commentary, p. 376), or, in Edward Casey’s text: ‘That is what place is: the first unchangeable limit (peras) of that which surrounds’ in Edward S. Casey, The Fate of Place: A Philosophical History (Berkeley: University of California Press, 1997), 55.
 This characterization of peras as limit is close but different with respect to the more famous statement included in the popular essay Building Dwelling Thinking, where peras is characterized as ‘boundary’ — see note  below. I have found this alternative Heideggerian characterization of peras as limit in Malpas’s text Heidegger and the Thinking of Place, note 56, pages 288-289. My quote is taken from the original translation of Parmenides made by André Schuwer and Richard Rojcewicz, page 82.
 Concerning the concepts of limit, margin, edge, boundary, border, and similar liminal notions in connection with spatial/placial questions this is an issue especially considered by the American philosopher Edward S. Casey: see his website — https://www.escasey.com/articles — for an extended list of works. In particular, Casey is focused on the concept of edge, which, Casey argues, is the basic notion for understanding things, bodies and places; whether he says ‘Edges Everywhere’ — in the essay Being on the Edge: Body, Place, Climate, see below —, I have spoken of Places Everywhere. I think there is a certain affinity between the two positions, maybe one could see a correlation given that, at least for me, edges and places are correlated notions; so, for instance, where Casey speaks of edges as integral elements of fire, air, earth and water (in the aforementioned essay, page 458), I speak of the same elements as physicochemical states of place; where Casey says that these elemental-edges are co-ingredient of life, I say that these physicochemical states places are co-ingredient of biological states of place (the genealogy of places I have envisioned extends its encompassing arc to include symbolic states of place, passing through sociocultural states of place). I have singled out some of Casey’s works which are quite pertinent with respect to the present article and my work in general: Edward S. Casey, “Borders ad Boundaries: Edging into the Environment”, in Merleau-Ponty and Environmental Philosophy, eds. Suzanne L. Cataldi and William S. Hamrick (New York: SUNY Press, 2007), 67-92; Edward S. Casey, “Boundary, Place, and Event in the Spatiality of History”, in Rethinking History 11, no.4 (2007), 507-512; Edward S. Casey, “Place and Edge”, in The Intelligence of Place: Topographies and Poetics, ed. Jeff Malpas (London: Bloomsbury, 2015), 23-38; Edward S. Casey, “Being on the Edge: Body, Place, Climate”, in Place, Space and hermeneutics, ed. Bruce B. Janz, (Cham: Springer International Publishing AG, 2017), 451-463. Another important philosophical contribution to the question of limits and their practical implications is Massimo Cacciari’s essay “Place and Limit”, in The Intelligence of Place: Topographies and Poetics, ed. Jeff Malpas (London: Bloomsbury, 2015), 13-22. The metaphysical question concerning the notion of limit is especially considered by Jeff Malpas in the chapter Ground, Unity and Limit in Heidegger and the Thinking of Place: Explorations in the Topology of Being (Cambridge: the MIT Press, 2012), 73-95. Another interesting contribution on the question of limits and their practical spatial/placial implications in the wake of Cacciari’s argumentation is the essay by Søren Tinning, “Place, Public Space and the Limits Defining them: a Heideggerian Approach”, in Philosophical Path in the Public Sphere, eds. Gaetano Chiurazzi, Davide Sisto, Søren Tinning (Zurich: Lit Verlag, 2012), 99-116. I agree with Tinning’s conclusions: ‘we should insist precisely therefore on questioning them [public spaces] as places rather than spaces’ (p. 115), which is something I also have sustained from my perspective of an architect, in the article Urban Spaces or Places?
 The name ‘archi-textures’ was suggested to me by the reading of Lefebvre’s book ‘The Production of Space’, where he says that ‘it is helpful to think of architectures as “archi-textures”, to treat each monument or building, viewed in its surroundings and context, in the populated area and associated networks in which it is set down’, in Henry Lefebvre, The Production of Space, translated by D. Nicholson-Smith (Oxford: Basil Blackwell, Inc., 1991), 118. That conceptualization perfectly adapts to the meaning I attribute to architecture, which cannot be thought of in abstraction of its actual context (which is always a place, not space). For a concrete example of what I mean for that expression — ‘archi-textures’ — look at the following video clips Space and Place: The Rainbow School and Space and Place: Växjö Tennis Hall, which showcase the making of two projects, both awarded with the World Architecture Community Awards. Archi-textures are a type of architectural text made of 2D and 3D lines, surfaces and volumes which compose a real three-dimensional texture. This architectural text or texture stands in the middle range between the realm of space (which is ideal, potential and abstract) and the realm of place (which is physical, actual and concrete, to begin with); it is a third genus or realm which can probably give you an idea of what Plato meant by ‘chōra’ (at this regards, look at the video clip Concrete Geometries, which is another example of what I mean for ‘archi-textures’). On the meaning of ‘archi-textures’ see also the notes  and , below.
 At this regard, the American psychologist James J. Gibson is quite explicit in his introduction to what I consider a pioneering work in the field of perception and cognition — The Ecological Approach to Visual Perception. Gibson writes: ‘I am also asking the reader to suppose that the concept of space has nothing to do with perception. Geometrical space is a pure abstraction. Outer space can be visualized but cannot be seen. The cues for depth refer only to paintings, nothing more. The visual third dimension is a misapplication of Descartes’s notion of three axes for a coordinate system. The doctrine that we could not perceive the world around us unless we already had the concept of space is nonsense. It is quite the other way around: We could not conceive of empty space unless we could see the ground under our feet and the sky above. Space is a myth, a ghost, a fiction for geometers. All that sounds very strange, no doubt, but I urge the reader to entertain the hypothesis’. In James J. Gibson, The Ecological Approach to Visual Perception (New York: Psychology Press Classic Editions, 2015), xv, xvi. I surely couldn’t have overthrown my understanding of space — and consequently of place — were it not for those words and the clear-cut logic behind them. You certainly understand that what is at stake, here, is either the overthrowing of a system of knowledge dominated, for centuries, by Newton, Kant and, more recently, by Einstein, or the overthrowing of the sense of their spatial vocabulary. In any case, this is a hard matter for architects… But how can architects approach architecture if the tools they work with — space, place and matter, to begin with — refer to unclarified notions? This is basically the reason for my research: to elucidate the senses of place and space (and consequently of matter and time) at the dawn of a new era, the Anthropocene.
 The American ecologists E.P. Odum and G.W. Barrett, in the book Fundamentals of Ecology, by relying on a scheme elaborated by the Austrian astrophysicist and polymath Erich Jantsch, defined interdisciplinarity as the interaction between different disciplines coordinated by a single discipline; while they defined transdisciplinarity as the coordination of an entire system of knowledge which regards the integration, at different levels, between many disciplines (I have read the Italian edition of that book: Fondamenti di Ecologia, Piccin Nuova Libreria, 2007; you can find that scheme on page 15). Concerning the important question of interdisciplinarity and/or transdisciplinarity, I want to say that we have already seen the opportunities and the limits of a system of knowledge based on the work of specialists and corresponding reductionist approaches (a method that we can trace back to Descartes and Newton). The new epoch, whose complex problems transcend usual boundaries (geographical, ecological, social, political, economic, cultural boundaries) necessitates to integrate the work of specialists within a bigger framework, where reductionism is correlated to a more holistic vision of reality. The path between the four systems — physicochemical, biological, social and symbolic systems, which are the four seamless systems that, in this epoch, give the most complete image of reality as a unique encompassing realm or place — is circular; this means that any form of reductionism that is not correlated to a more holistic conception of life and the Cosmos is a dead end and can hardly give us any valuable contributions to expand the edge of knowledge (a transdisciplinary approach is inherently anti-reductionist, given that it understands the contribution of any discipline within a more encompassing integrate perspective). The overall conception of knowledge that I’m proposing here is fundamentally systemic and ecological (in this case by the term ‘ecological’ I’m referring to the way ecology is structured as a discipline), therefore it is intrinsically transdisciplinary, as well as systemic and ecological is my proposal concerning the reformulation of the concepts of space and place: places and their boundaries work the same way ecological levels of organization work, from the cell to the ecosphere passing through the organism and populations; yet, I extended this system to encompass physicochemical systems — down to the fields of physics and up to the Cosmos, including what is distinctive of the humankind: the mind with any of its abstract products (space — the three-dimensional container — is certainly one of the most important products). Transdisciplinarity is the method through which cultivating this new awareness concerning the fundamental bond between different yet equally fundamental levels (equiprimordiality between physicochemical, biological, social and symbolic levels) that are jointly constitutive elements of reality-as-place; we should understand the limits or boundaries between levels as distinctions within a common, encompassing horizon: limit as terminus and cum-finis.
 Merritt Ruhlen, The Origin of Language (New York: John Wiley & Sons, Inc., 1994), vii.
 Ibid., 8.
 See, the terms ‘apparens, entis’ and ‘appareo, ere’, the Oxford Latin Dictionary (Oxford: Oxford University Press, 1968), 149.
 Peras ‘end, boundary’, from peirar. Etymology: from the root *per- ‘to cross, pass through’, in Robert Beekes, Etymological Dictionary of Greek (Leiden: Brill, 2010), 1163, 1175.
 French philosopher Jacques Derrida writes: ‘In Plato’s text, chōra is compared to a sieve which separates things into the world of the sensible and intelligible’, in Jacques Derrida and Peter Eisenman, Chora L Works, edited by Jeffrey Kipnis and Tomas Leeser (New York: The Monacelli Press, 1997), 92.
 The reference is to the overall argumentation sustained by the Anglo-American philosopher and mathematician Alfred North Whitehead in the book Process and Reality. At this point, it seems to me it is necessary to discern between the sense of the term reality according to Whitehead, which reflects the common sense, and the sense of reality according to Kant, which, sometimes, I also refer to, and which is more ‘technical’, given that within the domain of reality Kant includes both actual and ideal or potential entities (see the article What is a Thing?).
 This is a possibility that I began to entertain after reading Jeff Malpas’s chapter ‘Ground, Unity, and Limit’ in Heidegger and the Thinking of Place: Explorations in the Topology of Being. Here, we read: ‘Heidegger talks of the happening of truth as aletheia in terms of “clearing” or “lighting” (Lichtung)’; then Malpas quotes an extended passage from Heidegger that I report here: ‘In the midst of beings as a whole an open place comes to presence. There is a clearing [Lichtung]. . . The being can only be, as a being, if it stands within, and stands out within, what is illuminated in this clearing. Only this clearing grants us human beings access to those beings that we ourselves are not and admittance to the being that we ourselves are. Thanks to this clearing, beings are unconcealed in certain and changing degrees. But even to be concealed, is something the being can only do within the scope of the illuminated. Each being which we encounter and which encounters us maintains this strange opposition of presence in that at the same time it always holds itself back in a concealment’, in Jeff Malpas, Heidegger and the Thinking of Place: Explorations in the Topology of Being (Cambridge: the MIT Press, 2012), 89-90. According to my understanding of reality as the place of actualized processes, this ‘clearing’ or ‘lighting’ can be interpreted as the moment in which processes (which are intrinsically concealed entities) are actualized in the form of appearances within limits (beings or entities as physicochemical, biological, social and symbolic states of place), which presuppose that the territory once occupied by processes is cleared out so that beings can appear within their respective limits as an immediate form of lighting. I read Heidegger’s question of truth behind this narration as the moment of genuine union between processes (that which is concealed) and reality (in the sense of that which is unconcealed, a concrete state): only after unveiling the correlation between these two moments is truth possible, and can we have a genuine grasp of reality, as composite but unitary structure (reality is the place where the actual and the potential or ideal meet). This truth is reflected into my structuring of reality as jointly constitutive states of place that ultimately gather into a single but composite unit, or place; then, the structure of place (and space) that I propose is nothing less than the unconcealment of the abstract values of reality (all processes exist in the spatial realm of that which is intelligible) into more concrete values that exist in the placial realm of that which is sensible (processes actualized into concrete entities within discernible limits). I think the following words pronounced by Malpas, while he attempts to elucidate Heidegger’s understanding of aletheia (in Heidegger and the Thinking of Place, page 91), are perfect to elucidate the basic theme of my article: ‘the coming to appearance of things is thus a matter of their coming out of their prior concealment, but such revealing is precisely a matter of demarcation and limit since “Where demarcation is lacking, [this is Heidegger who is speaking – see the reference to note 3] nothing can come to presence as that which it is”. Limit is part of the very structure of unconcealment or presence’. Few lines after, always in reference to the question of aletheia and Heidegger’s thinking about the connection between ‘ground’, ‘unity’ and ‘limit’, Malpas directly characterizes Heidegger’s thinking in placial terms (a position I’m very close to): ‘the “clearing of being” is immediately suggestive of topos: the clearing of being is the topos of being, and the “saying” of the clearing is thus also a saying of the topos, the place, of being’, page 92.
 On the notion of limit as terminus see also the interpretation offered by Malpas’s reading of Aristotle and Kant: in Jeff Malpas, Heidegger and the Thinking of Place: Explorations in the Topology of Being (Cambridge: the MIT Press, 2012), 84, 287.
 See the article What Is a Thing? Heidegger’s conception of the thing instantiates the intrinsic relationality between object and subject, bypassing their epistemological and physical distance created by their finitude; that distance, a condition of their limits, is also seen as a moment of union. Later, this question will be explicated by Heidegger’s famous statement, in the essay Building Dwelling Thinking: ‘a boundary is not that at which something stops but, as the Greeks recognized, the boundary is that from which something begins its presencing’, Martin Heidegger, in Basic Writings (New York: HarperCollins Publishers, 1993), 356. Therefore, a limit can also be thought of as a moment of distinction within a more encompassing, unifying horizon: at the same time, terminus and cum-finis.
 See Edward S. Casey, “Borders ad Boundaries: Edging into the Environment”, in Merleau-Ponty and Environmental Philosophy, eds. Suzanne L. Cataldi and William S. Hamrick (New York: SUNY Press, 2007), 67-92; the statement concerning ‘compenetrative presences’ is on page 81. In general, we have to remark that the very essence of many phenomenological accounts of reality resides in the denial of any abrupt form of separation between object and subject (or between object themselves) as a fundamental condition to guarantee the continuity of experience. This issue was especially evident in Husserl, in the late Heidegger, as well as in Merleau-Ponty. This fundamental ‘continuity’ is what I also have tried to translate in architectural terms by means of the so-called ‘archi-textures’ which are literally the representation of reality as a closely woven fabric where any bifurcation between subject and object almost dissolves into a web of pure relations seeking a form (see notes 5, above, and 19, below).
 I began to develop my reformed idea of place starting from architectural considerations: if we come back to my notion of archi-textures, see the notes  and  above, these are simply a way to connect the subject to the objects around (the World as physical environment), within a seamless unit of place, or experience. In the wake of a phenomenological approach to knowledge, I thought of the limit between the subject and the world around as a moment of complete union, rather than a separation, to the point that I almost dissolved that limit, exposing only relations which directly connect the perceiving subject to the world around, understood as the primary source of sensory stimulation. In this way, I recombined and recovered the spatial distance between the subject and the objects composing the world around in the form of a placial union. Then, those relations expressed in terms of lines and surfaces, taken together, compose an architectural text, a real three-dimensional texture, which narrates the encounter between the subject and the World of objects all around the subject. To put it another way, the nexus between the perceiving subject and the objects around — i.e. myself in the act of analysing the existing place of the project, and its components, streets, facades, trees, their textures, the exposure to the sun and wind, etc. —, is explicated by means of 2D and 3D lines and surfaces (or volumes) which represent optic arrays, auditory fields, haptic relations, traces of bodily movements, or even the sun and wind paths, etc. connecting the body to the sources of stimulation (the World of objects or the environment around); those relations are the modality through which the encounter between subject and object is narrated — a moment of union rather than a separation; neither objects nor subject, yet both objects and subject. Fundamentally, I developed this modality of archi-textural expression as an ecological approach to the perception of the environment (after my first phenomenological investigations into the works of Husserl, Heidegger and Merleau-Ponty, the decisive step to give a definite architectural form to those investigations was my encounter with the work of the American psychologist James J. Gibson, The Senses Considered as Perceptual Systems). At the beginning of the design process, lines and surfaces are the tokens that represent the way subject and objects are connected through the subject’s senses and movements; with the progressive stratifications of the design process (with the stratification of physicochemical, biological, social and symbolic considerations), new lines, surfaces and volumes superimpose old relations becoming objects themselves that reify relations into basic architectural components (walls, floors, ceilings, etc. — for some examples of this architectural texts or textures, see the videos I mentioned in the note 5, above). In the overall, independently of the architect’s approach, and within an encompassing systemic perspective of life and the Cosmos, architecture should be understood as the process of reification of certain placial and spatial relations (physicochemical, biological, social and symbolic relations) with the ultimate scope of creating new spaces and modifying existing places for dwelling. This means that architecture cannot be reduced to place or space only, but it should be understood as an encompassing event that integrates those two different modalities of being — the concrete (place) and the abstract (space).
 Massimo Cacciari, “Place and Limit”, in The Intelligence of Place: Topographies and Poetics, ed. Jeff Malpas (London: Bloomsbury, 2015), 13.
 On the distinction between ‘boundary’ and ‘border’ see especially Edward S. Casey, “Boundary, Place, and Event in the Spatiality of History”, in Rethinking History 11, no.4, (2007), 508; Edward S. Casey, “Borders ad Boundaries: Edging into the Environment”, in Merleau-Ponty and Environmental Philosophy, eds. Suzanne L. Cataldi and William S. Hamrick (New York: SUNY Press, 2007), 73.
 Within a systemic perspective, the degree of autonomy of an emergent entity with respect to its substrate is not an easy question. In the case of a living organism, which is a complex system, we cannot understand the organism as the sum of metabolic processes, even if metabolic processes (physicochemical processes) subtend the behaviour of the organism as a superior biological entity (the place of biological processes). A biological entity is an autonomous entity — an autopoietic system — with respect to the substrate it emerges from (physicochemical systems), and this fact avoids old forms of determinism and reductionism. The same holds for all of the levels of reality. Yet, the degree of autonomy between two contiguous systems or levels is a matter of debate (again a question of limit or thresholds). I use a statement made by the American philosopher and novelist Robert M. Pirsig to say that the four systems ‘operate at the same time and in ways that are almost independent of each other’ (where I speak of physicochemical, biological, social and intellectual systems, Pirsig, whose work initially inspired me, speaks of inorganic, biological, social and intellectual static patterns of value). Here, the keyword is ‘almost’, which certainly implies independence between different levels of reality, or systems (or static patterns of value), but which does not exclude a certain degree of resistance of lower levels with respect to the independence of higher levels. There is a perennial fight to claim autonomy/dependence between levels, or to quote another passage from Pirsig: ‘The higher level can often be seen to be in opposition to the lower level, dominating it, controlling it where possible for its own purposes’. Where possible: for me, that possibility is a question of thresholds or limits; terminus and cum-finis, at the same time, or independence within a common horizon. Citations from Robert M. Pirsig, Lila: An Inquiry into Morals (v. 1.0, Corgi Edition, 1992), 73. This is certainly a question I will return on in the future, given that the entire framework of my reformed understanding of place and space, which is based on a systemic understanding of reality and knowledge, is directly affected by this question.
 A double limitation is at stake, here: one more concrete — the body/mind as a limited biological entity —, the other more abstract, in the sense explained by Kant. The latter sense concerning the limits of knowledge — the place of reason — is investigated by Jeff Malpas in Chapter 4 of the book Heidegger and the Thinking of Place: Explorations in the Topology of Being (more generally, in the wake of Kant and Heidegger, Malpas’s work is devoted to the topographical exploration of the limits of knowledge, in terms of integration-correlation between place and space, concreteness and abstraction, objectivity and subjectivity). Kant’s mapping of the territory of knowledge is one of the many possible exemplifications of what I mean when I speak of symbolic or intellectual states of place, given that knowledge itself is a place and Kant, with his work, delineated its boundaries or limits (precisely, knowledge is the place of intellectual or symbolic processes which resume and transcend physicochemical, biological and sociocultural limits).
 For details concerning the limits of Aristotle’s definition of place see the part concerning Aristotle in the article Space and Place: A Scientific History – Part I.
 At any concrete or actual level of reality, there is not a ‘physical’ line that separates bodies, just exchange of forces — physical fields — between electrons that do not allow two different bodies or their parts to occupy the same place at the same time (this is logically excluded if we admit that concrete entities/bodies are the place of actualized processes having an extension, duration and localization —which can be either a pinpoint location or an extended location in the same sense a field is extended).
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