Full Idea
For Pythagoreans the entire universe is constructed from numbers.
Gist of Idea
Pythagoreans say the whole universe is made of numbers
Source
Aristotle (Metaphysics [c.324 BCE], 1080b16)
Book Reference
Aristotle: 'Metaphysics', ed/tr. Lawson-Tancred,Hugh [Penguin 1998], p.409
A Reaction
The original view seems to have been more extreme than the mere idea that mathematics is the guide to nature, or the language of God. Stones are made of numbers. Aristotle was unimpressed.