Full Idea
The whole does not consist of parts; for it did, it would be all the parts and so would be the sum.
Gist of Idea
The whole can't be the parts, because it would be all of the parts, which is the whole
Source
Plato (Theaetetus [c.364 BCE], 204e)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.227
A Reaction
That is, 'the whole is the sum of its parts' is a tautology! The claim that 'the whole is more than the sum of its parts' gets into similar trouble. See Verity Harte on this.