This main part of this entry follows (with varying degrees of accuracy), John Philoponus, Commentary on Aristotle's de anima: first (as far as 'the separated [form]') an approximation of 204.15-34; then (as far as 'holds it together') a closer version of 208.37 - 209.3; and for 'statue' cf. 211.22. The example of the sailor to illustrate the separation of the form (understood in terms of actuality) from the body is repeated by Philoponus throughout his commentary. See also Aristotle, De anima 414a25-27, a passage which is close in meaning both to Philoponus' and the Suda's text.
cf. delta 1573.
[1] In Aristotle’s model of change the substratum is the matter, that which underlies the process of change and out of which something comes to be. Aristotle’s scheme of change involves three factors: (1) the substratum, (2) the privation, and (3) the form -- the privation and the form being 'the opposites' (Physics 191a3-5). Any change is understood as a motion 'coming from something and going toward something', so that the contraries or opposites constitute the limit of any change (Physics 252b10-12; Metaphysics 1033a24-28 (web address 1)). Matter (or the substratum) is what changes, since it is both contraries in potentiality (Metaphysics 1069b7-18 (web address 2)). Now the privation (ste/rhsis) and the form should be understood as being "two forms". Privation is a sort of “negative form” (such as “unmusical” said of a man, which is the substratum, or "shapelessness" or "formlessness" said of the bronze or the stone, which are their substrata; Physics 190b13-17), and form is a "positive form or the form in the strict sense", that is, the positive determination the object will have at the end of the process of change. And this is so, Aristotle says, because in every process of change there is a substratum having a form and, in the course of the change, such a substratum loses that form and acquires another one. A man (an individual substance), for instance, in being unmusical, becomes musical (qualitative change), or an undetermined substratum, in not being a man, becomes a man (substantial change). Now matter is, by definition, something passive which by itself is not said as something determined (Metaphysics 1042a27-28 (web address 3)), something that, "without being a 'this' in actuality is a 'this' in potentiality" (mh\ to/de ti ou)=sa e)nergei/a| duna/mei e)sti\ to/de ti). The active principle of the process is the form (insofar as it is what actualizes or gives complete reality to matter when making it a defined object), which is identified with actuality. Thus Aristotle can say that a particular thing (such as a bed, flesh, or bone) is not that particular thing if it is what it is only in potentiality and has not yet the form of the particular thing. So the form both actualizes the possibility of being of some substratum and it is that by which we, in making a definition, say what flesh or bone are (Physics 193a33-b3).
[2] The issue of the separation of the form goes back to Plato and is a very important aspect of the dispute between Plato and Aristotle. The Platonic thesis that Forms are separated from the particulars is vigorously rejected by Aristotle (see for example Metaphysics 1033b20-21 (web address 4)). Although Aristotle admits the Platonic assertion that the object of knowledge is the universal, he thinks Plato is wrong in considering that the universal (i.e. the way in which Aristotle understands Plato's Forms) must exist separately or beyond the sensible particulars (Metaphysics 990b11-31 (web address 5)). In Aristotle's view Platonic Forms are pointless because the separated form does not contribute to account for the particulars (Metaphysics 990a34-b8). For other details of Aristotle's criticisms see Metaphysics 1.9, 13.4-5 and the illuminating account of the criticisms by Berti [1977], 196-230). Now, even though Aristotle rejects the allegedly Platonic separation between Forms and sensible things (since if the form were separated from the particular, it might not be present in a multiplicity of things), he admits a certain type of separation: a conceptual or logical separation (Physics 193b4-5; Metaphysics 1042a28-29).
[3] That is to say, each thing is named according to its own form, not according to its matter (see above, note 1).
[4] Porphyry [pi 2098, pi 2099], On Aristotle's Categories (vol 4.1 Busse) p.55.20.