I have deeply regretted that I did not proceed far enough at least to understand something of the great leading principles of mathematics, for men thus endowed seem to have an extra sense.

There is no fundamental difference between man and animals in their ability to feel pleasure and pain, happiness, and misery.

The more we know of the fixed laws of nature the more incredible do miracles become, - that the men at that time were ignorant and credulous to a degree almost incomprehensible by us, - that the Gospels cannot be proved to have been written simultaneously with the events, - that they differ in many important details, far too important as it seemed to me to be admitted as the usual inaccuracies of eye-witnesses; - by such reflections as these... I gradually came to disbelieve in Christianity as a divine revelation.

That there is much suffering in the world no one disputes. Which is more likely, that pain and evil are the result of an all-powerful and good God, or the product of uncaring natural forces? The presence of much suffering agrees well with the view that all organic beings have been developed through variation and natural selection.

Progress has been much more general than retrogression

Blushing is the most peculiar and most human of all expressions.

Although I am fully convinced of the truth of the views given in this volume under the form of an abstract, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine... I look with confidence to the future, to young and rising naturalists, who will be able to view both sides of the question with impartiality.