Mathematics is the only good metaphysics.

There is nothing in science which teaches the origin of anything at all.

Heavier-than-air flying machines are impossible.

There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.

At what time does the dissipation of energy begin?

[Referring to Fourier's mathematical theory of the conduction of heat] ... Fourier's great mathematical poem.

I need scarcely say that the beginning and maintenance of life on earth is absolutely and infinitely beyond the range of all sound speculation in dynamical science. The only contribution of dynamics to theoretical biology is absolute negation of automatic commencement or automatic maintenance of life.