Full Idea
The whole of which the parts are parts must be one thing composed of many; for each of the parts must be part, not of a many, but of a whole.
Gist of Idea
Anything which has parts must be one thing, and parts are of a one, not of a many
Source
Plato (Parmenides [c.364 BCE], 157c)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.389
A Reaction
This is a key move of metaphysics, and we should hang on to it. The other way madness lies.
Related Idea
Idea 15849 Plato says only a one has parts, and a many does not [Plato, by Harte,V]