I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild duck; and this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parents.

I always feel as if my books came half out of Lyell's brain... & therefore that when seeing a thing never seen by Lyell, one yet saw it partially through his eyes.

It is a fatal fault to reason whilst observing, though so necessary beforehand and so useful afterwards.

During my second year at Edinburgh [1826-27] I attended Jameson's lectures on Geology and Zoology, but they were incredible dull. The sole effect they produced on me was the determination never as long as I lived to read a book on Geology.

The more efficient causes of progress seem to consist of a good education during youth whilst the brain is impressible, and of a high standard of excellence, inculcated by the ablest and best men, embodied in the laws, customs and traditions of the nation, and enforced by public opinion.

Free will is to mind what chance is to matter.

Man selects only for his own good: Nature only for that of the being which she tends.