Timaeus introduces the divine craftsman he calls “poet and father'' of all that comes to be. (28e)

He does not attempt to demonstrate or prove or defend the existence of the craftsman. We are led to ask how Timaeus knows of him. The suspicion is that Timaeus is the craftsman, the poet and father, of the divine craftsman. — Fooloso4

So then, Socrates, if, in saying many things on many topics concerning gods and the birth of the all, we prove to be incapable of rendering speeches that are always and in all respects in agreement with themselves and drawn with precision, don’t be surprised. But if we provide likelihoods inferior to none, we should be well-pleased with them, remembering that I who speak as well as you my judges have a human nature, so that it’s fitting for us to be receptive to the likely story about these things and not search further for anything beyond it. (29c-d).

His imprecision is seen here as well:

As for all the heaven (or cosmos, or whatever else it might be most receptive to being called, let us call it that) … (28b).

Why not be more precise? Isn’t it imperative to be precise in matters of metaphysics and cosmogony?

We are human beings, capable of telling likely stories, but incapable of discerning the truth of such things. In line with the dialogues theme of what is best, Timaeus proposes it is best to accept likely stories and not search for what is beyond the limits of our understanding. — Fooloso4

And that which has come into existence must necessarily, as we say, have come into existence by reason of some Cause. Now to discover the Maker and Father of this Universe were a task indeed; and having discovered Him, to declare Him unto all men were a thing impossible (Timaeus 28c).

ποιητής
A maker, μηχανημάτων Id.Cyr.1.6.38; κλίνης Pl.R.597d; τὸν π. καὶ πατέρα τοῦδε τοῦ παντός Id.Ti.28c

Making use, then, of the causes mentioned our Maker (poion) fashioned the head shaggy with hair … (Tim. 76c)

I simply, naively and perhaps foolishly cling to this, that nothing else makes it beautiful other than the presence of, or the sharing in, or however you may describe its relationship to that Beautiful we mentioned, for I will not insist on the precise nature of the relationship, but that all beautiful things are beautiful by the Beautiful. (100e)

each element of an indeterminate dyad is one, but both are two.

It may appear as though the Timaeus is a departure for Plato, but it is consistent with Socratic skepticism. An indeterminate world, one where chance and contingency play a role, is a world that cannot be known. An indeterminate world of chance and contingency is one where the unknowable, the mystical dimension of life, is not flattened and destroyed. — Fooloso4

Consequently, even if knowledge of the Forms is possible it cannot give us knowledge of the sensible world. — Fooloso4

So it sounds like Plato had the sceptic and mystic elements in his thoughts on the world, human life and the gods. — Corvus

So then, Socrates, if, in saying many things on many topics concerning gods and the birth of the all, we prove to be incapable of rendering speeches that are always and in all respects in agreement with themselves and drawn with precision, don’t be surprised. But if we provide likelihoods inferior to none, we should be well-pleased with them, remembering that I who speak as well as you my judges have a human nature, so that it’s fitting for us to be receptive to the likely story about these things and not search further for anything beyond it.

... it’s fitting for us to be receptive to the likely story about these things and not search further for anything beyond it.

Excellent Timaeus! And it must be received entirely as you urge.

This is why Plato in the Timaeus says that matter and space are the same; for the 'participant' and space are identical. (It is true, indeed, that the account he gives there of the 'participant' is different from what he says in his so-called 'unwritten teaching'. Nevertheless, he did identify place and space.) I mention Plato because, while all hold place to be something, he alone tried to say what it is.* — Count Timothy von Icarus

The term'mystic' has been used to mean what is beyond our knowledge and understanding and also to mean what the mystic knows through transcendent experience,. I think Plato points to the former and provides a myth about the latter. — Fooloso4

Well, Aristotle's notion of matter is much different from modern physics, and is perhaps more usefully likened to energy. — Count Timothy von Icarus

But, the "void," space, does seem to "weigh." — Count Timothy von Icarus

Frank Wilzek's "The Lightness of Being," is a really great book on the properties of "empty space," and he makes the argument that theories of aether might be usefully employed for understanding this "metric field." — Count Timothy von Icarus

Clearly we should now begin again, once we have called upon the god, our saviour, at the very outset of our deliberations to see us safely out of an unusual and unaccustomed exposition, to the doctrine of things probable. In any case, our fresh start concerning the universe should be more elaborate than before, for we distinguished two entities then, but now we must present a third factor. Two were sufficient for our previous descriptions, one designated as a sort of a model discernible by Nous and ever the same, while the second was a copy of the model involved in becoming and visible. We did not distinguish a third entity at the time as we thought it enough to have these two, but now the argument seems to compel us to try to manifest a difficult and obscure form in words. What should we understand its capacity and nature to be? This in particular: it is the receptacle of all coming into being, like its nurse. Now although the truth has been spoken, a clearer statement about it is still required but it is difficult to do so, particularly because it is necessary for the sake of this to raise a preliminary problem about fire and its accompaniments. It is difficult in the case of each of these to state what sort should actually be called water rather than fire, and what sort should be referred to as anything in particular rather than as everything individually, in such a manner as to employ language which is trustworthy and certain. How then, may we speak about them in a likely manner and in what way, and what can we say about them when faced with this problem? — Plato, Timaeus, 48e, translated by Horan

For, according to Aristotle, this is what Plato declared the receptacle to be: “a substratum [ύποκείμενον] prior to the so-called elements, just as gold is the substratum of works made of gold.” Though in this context Aristotle refers to one other image of the χώρα, that of nurse (τιθήνη), he forgoes drawing on the content of that image and, instead, moves immediately to identify the receptacle with “primary matter” (329a). Yet the passage that is, at once, both most decisive and most puzzling occurs in Book 4 of the Physics: “This is why Plato says in the Timaeus that matter and the χώρα are the same; for the receptive and the χώρα are one and the same. Although the manner in which he speaks about the receptive in the Timaeus differs from that in the so-called unwritten teachings, nevertheless he declares that place [τόπος] and the χώρα are the same” (209b).

One cannot but be struck by the lack of correspondence between this passage and the text of the Timaeus. The passage declares three identifications: that of the receptive (μεταληπτικόν) with the χώρα, that of matter (ύλη) with the χώρα, and that of place (τόπος) with the χώρα. Only the first of these identifications has any basis in the text of the Timaeus, and then only if one disregards any difference that might distinguish μεταληπτικόν from the Platonic words δεχόμενον and ύποδοχή.

For the identification of ύλη with the χώρα, there is no basis in the Timaeus. Plato never uses the word ύλη in Aristotle’s sense, a sense that, one suspects, comes to be constituted and delimited only in and through the work of Aristotle. When Plato does, on a few occasions, use the word, it has the common, everyday sense of building material such as wood, earth, or stone. Following Aristotle’s own strategy in On Generation and Corruption, one could refer to the image of the constantly remodeled gold as providing support for the identification. But reference to this image could be decisive only if one privileged it over most of the others, disregarding, for instance, the image of the nurse, which represents the relation between the χώρα and the sensible in a way quite irreducible to that between matter and the things formed from it. What is perhaps even more decisive is that all these are images of the χώρα, images declared in an είκώς λόγος (likely account}, which is to be distinguished from the bastardly discourse in which one would venture to say the χώρα. — John Sallis, Chorology: On Beginning in Plato's Timaeus

We have seen that attributions are made directly, in virtue of their immediate applicability, or mediately, because, though not immediately applicable themselves, they include, involve, or imply something that is immediately applicable. And so, too, a ‘place’ may be assigned to an object either primarily because it is its special and exclusive place, or mediately because it is ‘common’ to it and other things, or is the universal place that includes the proper places of all things.

I mean, for instance, that you, at this moment, are in the universe because you are in the air, which air is in the universe; and in the air because on the earth; and in like manner on the earth because on the special place which ‘contains and circumscribes you, and no other body.

But if what we mean by the ‘place’ of a body is its immediate envelope, then ‘place’ is a limiting determinant, which suggests that it is the specifying or moulding ‘form’ by which the concrete quantum, together with its component matter, is ‘determined.’ For it is just the office of a limit so to determine or mould something. From this point of view, then, we should identify ‘place’ with ‘form.

But if we think of a thing’s place as its ‘dimensionality’ or ‘room-occupancy’ (to be distinguished from the thing itself, as a concrete quantum) we must then regard it as ‘matter’ rather than as ‘form,’ for matter is the factor that is bounded and determined by the form, as a surface, or other limit, moulds and determines; for it is just that which is in itself undetermined, but capable of being determined, that we mean by matter. Thus, if a concrete sphere, e.g., be stripped of its limit, as well as of its other determining characteristics, nothing but its matter is left.

This is why Plato, in the Timaeus, identifies, a ‘matter’ and ‘room,’ because ‘room’ and ‘the receptive-of-determination’ are one and the same thing. His account of the ‘receptive’ differs in the Timaeus and in what are known as his Unwritten Teachings, but he is consistent in asserting the identity of ‘place’ (τόπον) and ‘room.’(χώραν) Thus, whereas everyone asserts the reality of ‘place,’ only Plato has so much as attempted to tell us what it is.

It is no wonder that, when thus regarded,—either as matter or as form, I mean,—‘place’ should seem hard to grasp, especially as matter and form themselves stand at the very apex of speculative thought, and cannot well, either of them, be cognized as existing apart from the other.

But in truth it is easy enough to see that its place cannot possibly be either the matter or the form of a thing; for neither of these is separable from the thing itself, as its place undoubtedly is. For we have already explained that ‘where’ the air was ‘there’, again the water is, when the water and air succeed each other, and so too with any other substance; and therefore its ‘place’ can be neither a factor nor an intrinsic possession of the thing, but is something separable from it. — Aristotle, Physics, 209a, translated by Wicksteed and Cornford

What makes the passage from Physics even more convoluted is that Aristotle is not actually agreeing with the view he ascribes to Plato regarding whether 'place' belongs to a being as its form and matter do: — Paine

This is why Plato, in the Timaeus, identifies, a ‘matter’ and ‘room,’ because ‘room’ and ‘the receptive-of-determination’ are one and the same thing. His account of the ‘receptive’ differs in the Timaeus and in what are known as his Unwritten Teachings, but he is consistent in asserting the identity of ‘place’ (τόπον) and ‘room.’(χώραν) Thus, whereas everyone asserts the reality of ‘place,’ only Plato has so much as attempted to tell us what it is. — Aristotle, Physics, 209a, translated by Wicksteed and Cornford