There is one living spirit, prevalent over this world ... which assumes a multitude of forms according to subordinate laws. There is one thinking sensible principle allied to one kind of organic matter.

We can allow satellites, planets, suns, universe, nay whole systems of universe, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

Our faculties are more fitted to recognize the wonderful structure of a beetle than a Universe.

I feel most deeply that this whole question of Creation is too profound for human intellect. A dog might as well speculate on the mind of Newton! Let each man hope and believe what he can.

Physiological experiment on animals is justifiable for real investigation, but not for mere damnable and detestable curiosity.

I love fools' experiments. I am always making them.