Full Idea
The most accurate philosophers have no other meaning annexed to 'material substance' but the idea of being in general, together with the relative notion of its supporting accidents.
Clarification
'Accidents' are properties
Gist of Idea
Material substance is just general existence which can have properties
Source
George Berkeley (The Principles of Human Knowledge [1710], §17)
Book Reference
Berkeley,George: 'The Principles of Human Knowledge etc.', ed/tr. Warnock,G.J. [Fontana 1962], p.72
A Reaction
This is part of the attack on Aristotle's concept of 'substance', and is a nice way of dissolving the concept. 'Substance' will never reappear in physics, but modern philosopher have returned to it, as possibly inescapable in metaphysics.