"The term 'substance' is one of the most confusing terms in philosophy. For Aristotle, at least some of the time, the paradigm cases of substances were, as he put it, 'this man,
this horse', i.e. particular things of that kind. For complicated historical reasons, however, substance has sometimes come to be equated with what Aristotle called 'matter'; thus iron and sulphur,
and other stuffs, have come to be called 'substances'. For further complicated historical reasons substance came to be regarded by e.g. Locke as the underlying something or other which is supposed to
give support to the properties that inhere in it. Indeed the Latin etymology of the term 'substance' will suggest to anyone having a sensitivity to it that notion of something standing beneath the
properties. Locke thus called it a 'something I know not what' -- a suggestion that is not conveyed by either of the other two usages. The situation is complicated still further by the fact that the
Latin etymology is relevant only to those modern discussions which rely on the term 'substance'. The Greek word which Aristotle used -- 'ousia' -- and which is traditionally translated 'substance'
has none of the suggestions that the Latin etymology of 'substance' provides, but has additional suggestions of its own, particularly a connexion with being. (The feminine present participle of the
verb 'to be' in Greek is ousia; ousia has the form of an abstract noun and is for that reason naturally to be translated 'being' or 'beingness', but Aristotle often uses the word with an article to
indicate a particular kind of being, a particular kind of thing.)"
From: David Hamlyn - Metaphysics - Cambridge, Cambridge University Press, 1984 p. 60.
"For Aristotle, 'substances' are the things which exist in their own right, both the logically ultimate subjects of predication and the ultimate objects of scientific inquiry. They
are the unified material objects, as well as the natural stuffs, identifiable in sense-experience, each taken to be a member of a natural species with its 'form' and functional essence. Entities in
other categories -- qualities, actions, relations and so forth -- are treated as dependent on, if not just abstracted aspects of, these independent realities. With the rise of mechanistic physics in
the seventeenth century, the Aristotelian multiplicity of substances was reduced to universal matter mechanically differentiated. This move sharpened the issue of the relation of mind to the physical
world. The consequent variety of ways in which the notion of substance was manipulated by materialists, dualists, immaterialists and anti-dogmatists encouraged later scepticism about the distinction
between independent realities and human abstractions, and so idealism. Twentieth-century conceptualism, like some earlier versions of idealism, rejects the distinction altogether, commonly ascribing
the logical priority of material things in natural language to the utility of a folk physics, as if they were the theoretical entities of everyday life. As such, their identity and existence are
determined only through applications of a theory outdated by modern science. Yet this 'top-down', holistic philosophy of language is belied by the detailed insights of traditional logic, which point
clearly to a 'bottom-up' account of classification and identity, that is an account which recognizes the possibility of perceptually picking out material objects prior to knowledge of their kind of
nature, and of subsequently classifying them. The idea that material things are theoretical entities, and that their individuation is accordingly kind-dependent, is a hangover from an atomistic
approach to perception which calls on theory to tie sensory information together. A more accurate understanding of sensation as the already integrated presentation of bodies in spatial relations to
one another and to the perceiver is consonant with the possibility denied by the idealist - namely, that, with respect of its primitive referents, language and thought are shaped around reality
itself, the independent objects given in active sense-experience. That the coherence or discrete unity of material objects has a physical explanation does not mean that physics explains it away."
From: Edward Craig (ed.) - Routledge Encyclopedia of Philosophy - London, Routledge, 1998 - article Substance by Michael R.
Ayers p. 205.