The whole aspect of the universe changes with this new conception. The idea of force governing the world, of pre-established law, preconceived harmony, disappears to make room for the harmony that Fourier had caught a glimpse of: the one which results from the disorderly and incoherent movements of numberless hosts of matter, each of which goes its own way and all of which hold each other in equilibrium.

Kropotkin here may be refering to the French scientist Joseph Fourier, and not the French social philosopher Charles Fourier - Anarchism: Its Philosophy and Ideal (1896)