Full Idea
A 'conception' of horse is a theory of what a horse is, or what it is to be a horse. The conception is in no way the same as the concept. The conception is of the concept.
Gist of Idea
A 'conception' of a horse is a full theory of what it is (and not just the 'concept')
Source
David Wiggins (Sameness and Substance [1980], 3.1)
Book Reference
Wiggins,David: 'Sameness and Substance' [Blackwell 1980], p.79
A Reaction
Wiggins sounds confident about a sharp distinction here, which I doubt, but some such distinction seems to required. I quite like Williams's 'fat' and 'thin' concepts.