Full Idea
We must think of the individual units of all four basic shapes as being far too small to be visible, and only becoming visible when massed together in large numbers.
Gist of Idea
We must consider the four basic shapes as too small to see, only becoming visible in large numbers
Source
Plato (Timaeus [c.362 BCE], 56c)
Book Reference
Plato: 'Timaeus and Critias', ed/tr. Lee,Desmond [Penguin 1971], p.79