“What wretched doings come from the ardor of fame; the love of truth alone would never make one man attack another bitterly.”

“Origin of man now proved. Metaphysics must flourish. He who understand baboon would do more towards metaphysics than Locke.”

“Origin of man now proved.—Metaphysics must flourish.—He who understands baboon would do more towards metaphysics than Locke.”

“But then with me the horrid doubt always arises whether the convictions of man's mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey's mind, if there are any convictions in such a mind?[To William Graham 3 July 1881]”

“The love for all living creatures is the most noble attribute of man.”

“False facts are highly injurious to the progress of science, for they often endure long; but false views, if supported by some evidence, do little harm, for everyone takes a salutary pleasure in proving their falseness; and when this is done, one path towards error is closed and the road to truth is often at the same time opened.”

“...But I own that I cannot see as plainly as others do, and as I should wish to do, evidence of design and beneficence on all sides of us. There seems to me too much misery in the world. I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of Caterpillars, or that a cat should play with mice... I feel most deeply that the whole subject is too profound for the human intellect. A dog might as well speculate on the mind of Newton. Let each man hope and believe what he can.”