I believe man . . . in the same predicament with other animals.

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

Man in his arrogance thinks himself a great work.

I believe that animals have descended from at most only four or five progenitors, and plants from an equal or lesser number.

The great variability of all the external differences between the races of man, likewise indicates that they cannot be of much importance; for if important, they would long ago have been either fixed and preserved, or eliminated.

In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.