About thirty years ago there was much talk that geologists ought only to observe and not theorise; and I well remember some one saying that at this rate a man might as well go into a gravel-pit and count the pebbles and describe the colours. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!

Extinction has only separated groups: it has by no means made them; for if every form which has ever lived on this earth were suddenly to reappear, though it would be quite impossible to give definitions by which each group could be distinguished from other groups, as all would blend together by steps as fine as those between the finest existing varieties, nevertheless a natural classification, or at least a natural arrangement, would be possible.

Linnaeus and Cuvier have been my two gods, though in very different ways, but they were mere schoolboys to old Aristotle.

In my simplicity, I remember wondering why every gentleman did not become an ornithologist.

On seeing the marsupials in Australia for the first time and comparing them to placental mammals: “An unbeliever . . . might exclaim 'Surely two distinct Creators must have been at work'”

Thus disbelief crept over me at a very slow rate, but at last was complete. The rate was so slow that I felt no distress, and have never since doubted even for a single second that my conclusion was correct.

I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations.