The Aristotelian notion of hylomorphism as popularized by Aquinas and other medieval authors involves the form/matter duality where the matter in question is not the atomist conception we learn in physics, but a kind of primordial clay that all forms are made of.

Has the clay metaphor ever been used by ancient and/or not-so-ancient authors to explain the aristotelian conception?

  • I think that the analaogy is not apt to describe the compelxity of A's theory of matter and form: "Matter can itself be divided into matter and form: for instance, bricks are made of clay, shaped into cuboid blocks. Again, clay has its own matter—mud, say—and so on." Commented Sep 18, 2017 at 16:07
  • This is promising but unfortunately this is a quotation from Stanford Encyclopedia of Philosophy whereas I was hoping for some ancient authors; perhaps Aristotle himself? Feel free to elaborate as an answer. @MauroALLEGRANZA Commented Sep 18, 2017 at 16:11
  • @MauroALLEGRANZA Aristotle himself says that "The underlying nature is known by analogy" (Physica 191a7-8), so analogy is necessary for understanding hylemorphism.
    – Geremia
    Commented Sep 18, 2017 at 18:35
  • 2
    I am not sure about the clay metaphor but to Aristotle "matter" is a relative term, wood, for example, is a form–matter composite that serves as the matter of a bed. What you have in mind is more like prime matter, "pure potentiality". Even so, forms are not made of matter, they are complementary aspects that fuse (his word was "entelechy") into form–matter composites that are real things. Pasnau's Form and Matter is a good source on evolution of the "matter" concept from Aristotle to modern times.
    – Conifold
    Commented Sep 18, 2017 at 20:15
  • @Conifold, the "relative" reading is not really relevant to medieval interpretations of hylomorphism (or hylomorphism), where the main concern was to find an "explanation" of the eucharist. Commented Jan 5 at 11:15

1 Answer 1


Aristotle wrote in Physica 191a7-8:

ἡ δὲ ὑποκειμένη φύσις ἐπιστητὴ κατ' ἀναλογίαν. ὡς γὰρ πρὸς ἀνδριάντα χαλκὸς ἢ πρὸς κλίνην ξύλον ἢ πρὸς τῶν ἄλλων τι τῶν ἐχόντων μορφὴν [ἡ ὕλη καὶ] τὸ ἄμορφον ἔχει πρὶν λαβεῖν τὴν μορφήν, οὕτως αὕτη πρὸς οὐσίαν ἔχει καὶ τὸ τόδε τι καὶ τὸ ὄν.

The underlying nature is an object of scientific knowledge, by an analogy. For as the bronze is to the statue, the wood to the bed, or the matter and the formless before receiving form to any thing which has form, so is the underlying nature to substance, i.e. the 'this' or existent.

St. Thomas Aquinas commentated on this (Commentary on Aristotle's Physics lib. 1 lect. 15 [118.]):

Deinde cum dicit: subiecta autem natura etc., manifestat praemissa principia. Et dicit quod natura quae primo subiicitur mutationi, idest materia prima, non potest sciri per seipsam, cum omne quod cognoscitur, cognoscatur per suam formam; materia autem prima consideratur subiecta omni formae. Sed scitur secundum analogiam, idest secundum proportionem. Sic enim cognoscimus quod lignum est aliquid praeter formam scamni et lecti, quia quandoque est sub una forma, quandoque sub alia. Cum igitur videamus hoc quod est aer quandoque fieri aquam, oportet dicere quod aliquid existens sub forma aeris, quandoque sit sub forma aquae: et sic illud est aliquid praeter formam aquae et praeter formam aeris, sicut lignum est aliquid praeter formam scamni et praeter formam lecti. Quod igitur sic se habet ad ipsas substantias naturales, sicut se habet aes ad statuam et lignum ad lectum, et quodlibet materiale et informe ad formam, hoc dicimus esse materiam primam.

Hoc igitur est unum principium naturae: quod non sic unum est sicut hoc aliquid, hoc est sicut aliquod individuum demonstratum, ita quod habeat formam et unitatem in actu; sed dicitur ens et unum inquantum est in potentia ad formam. Aliud autem principium est ratio vel forma: tertium autem est privatio, quae contrariatur formae. Et quomodo ista principia sint duo et quomodo tria, dictum est prius.

Next where he says, ‘The underlying nature ...’ (191 a 8), he clarifies the above-mentioned principles. He says that the nature which is first subject to mutation, i.e., primary matter, cannot be known of itself, since everything which is known is known through its form. Primary matter is, moreover, considered to be the subject of every form. But it is known by analogy, that is, according to proportion. For we know that wood is other than the form of a bench and a bed, for sometimes it underlies the one form, at other times the other. When, therefore, we see that air at times becomes water, it is necessary to say that there is something which sometimes exists under the form of air, and at other times under the form of water. And thus this something is other than the form of water and other than the form of air, as wood is something other than the form of a bench and other than the form of bed. This ‘something’, then, is related to these natural substances as bronze is related to the statue, and wood to the bed, and anything material and unformed to form. And this is called primary matter.

This, then, is one principle of nature. It is not one as a ‘this something’, that is, as some determinate individual, as though it had form and unity in act, but is rather called being and one insofar as it is in potency to form. The other principle, then, is the nature [ratio) or form, and the third is privation, which is contrary to the form. And how these principles are two and how they are three was explained above.’

Also, he uses a bronze statue analogy in his short work De Principiis Naturæ.

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