Full Idea
I do not accept or desire any other principle in physics than in geometry or abstract mathematics, because all the phenomena of nature may be explained by their means, and sure demonstrations can be given of them.
Gist of Idea
Physics only needs geometry or abstract mathematics, which can explain and demonstrate everything
Source
René Descartes (Principles of Philosophy [1646], 2.64), quoted by Peter Alexander - Ideas, Qualities and Corpuscles 7
Book Reference
Alexander,Peter: 'Ideas, Qualities and Corpuscles' [CUP 1985], p.164
A Reaction
This is his famous and rather extreme view, which might be described as hyper-pythagoreanism (by adding geometry to numbers). It seems to leave out matter, forces and activity.