Platonic realism
Plato had led the focused application of geometry, developed by Euclid, to explain the natural world. Yet by his view of nature, Plato regarded astronomy as similar to seeking a theoretical proof in geometry—abstract and not the real world—whereupon the mind's insights derived from a quest to hold other truths through the mind's probing of ethics and aesthetics would yield discovery of truths within the realm of Forms, outside space and time.