  Ancient Greek geometry was not the only source of later conceptions  of analysis, however. Plato may not have used the term  ‘analysis’ himself, but concern with definition was  central to his dialogues, and definitions have often been seen as  what ‘conceptual analysis’ should yield. The definition  of ‘knowledge’ as ‘justified true belief’ (or ‘true belief with an account’, in more Platonic terms) is perhaps the classic example. Plato's concern may have been with real rather than nominal definitions, with ‘essences’  rather than mental or linguistic contents (see the supplementary  section on   Plato),  but conceptual analysis, too, has frequently been given a  ‘realist’ construal. Certainly, the roots of conceptual  analysis can be traced back to Plato's search for definitions,  as we shall see in   Section 4  below.