[Referring to Fourier's mathematical theory of the conduction of heat] ... Fourier's great mathematical poem.
Heavier-than-air flying machines are impossible.
If you can not measure it, you can not improve it.
I can never satisfy myself until I can make a mechanical model of a thing. If I can make a mechanical model, I can understand it. As long as I cannot make a mechanical model all the way through I cannot understand.
Mathematics is the only good metaphysics.
The fact that mathematics does such a good job of describing the Universe is a mystery that we don't understand. And a debt that we will probably never be able to repay.