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.

If we can't express what we know in the form of numbers, we really don't know much about it.

At what time does the dissipation of energy begin?

Can you measure it? Can you express it in figures? Can you make a model of it? If not, your theory is apt to be based more upon imagination than upon knowledge.

The vortex theory [of the atom] is only a dream. Itself unproven, it can prove nothing, and any speculations founded upon it are mere dreams about dreams.

Fourier is a mathematical poem.

I believe that the more thoroughly science is studied, the further does it take us from anything comparable to atheism.