Full Idea
Aristotle implies that matter is parasitic on the being of what it potentially is. …Hence if something is treated as bronze it is regarded as a composite and not as matter; only if it is treated as potentially a statue is it regarded as matter.
Gist of Idea
In Aristotle, bronze only becomes 'matter' when it is potentially a statue
Source
report of Aristotle (Metaphysics [c.324 BCE], matter) by Mary Louise Gill - Aristotle on Substance Ch.1
Book Reference
Gill,Mary Louise: 'Aristotle on Substance: Paradox of Unity' [Princeton 1989], p.23
A Reaction
Note the distinction we should make of bronze as indeterminate 'stuff', and a lump of specific bronze, which might be a precondition for casting a statue. On Gill's reading, Greek 'matter' is much more specific than the modern word.