Full Idea
Thales says water is the first principle (which is why he declared the earth is on water); perhaps he concluded this from seeing that all food is moist.
Gist of Idea
Thales said water is the first principle, perhaps from observing that food is moist
Source
report of Thales (fragments/reports [c.585 BCE], A12) by Aristotle - Metaphysics 983b12
Book Reference
'The First Philosophers', ed/tr. Waterfield,Robin [OUP 2000], p.12