Full Idea
Whenever the maker of anything keeps his eye on the eternally unchanging and uses it as his pattern for the form and function of his product the result must be good.
Gist of Idea
Something will always be well-made if the maker keeps in mind the eternal underlying pattern
Source
Plato (Timaeus [c.362 BCE], 28b)
Book Reference
Plato: 'Timaeus and Critias', ed/tr. Lee,Desmond [Penguin 1971], p.40