... probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed.

From my early youth I have had the strongest desire to understand or explain whatever I observed. ... To group all facts under some general laws.

It appears to me (whether rightly or wrongly) that direct arguments against Christianity and theism produce hardly any effect on the public; and freedom of thought is best promoted by the gradual illumination of men's minds, which follows from the advance of science.

I long to set foot where no man has trod before.

The chief distinction in the intellectual powers of the two sexes is shown by mans attaining to a higher eminence, in whatever he takes up, than the woman. Whether deep thought, reason, or imagination or merely the use of the senses and hands.....We may also infer.....The average mental power in man must be above that of woman.

Animals manifestly enjoy excitement, and suffer from annul and may exhibit curiosity.

The love of a dog for his master is notorious; in the agony of death he has been known to caress his master, and everyone has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless he had a heart of stone, must have felt remorse to the last hour of his life.