Full Idea
Substances can survive a change in their parts in a way that a mere aggregate of parts.
Gist of Idea
Substances, unlike aggregates, can survive a change of parts
Source
Stephen Mumford (Metaphysics: a very short introduction [2012], 3)
Book Reference
Mumford,Stephen: 'Metaphysics: A Very Short Introduction' [OUP 2012], p.29
A Reaction
A simple but very important idea. If we then distinguish between 'substances' and 'aggregates' we get a much clearer grip on things. Is the Ship of Theseus a substance or an aggregate? There is no factual answer to that. What do you want to explain?