I was a young man with uninformed ideas. I threw out queries, suggestions, wondering all the time over everything; and to my astonishment the ideas took like wildfire. People made a religion of them.

Even the humblest mammal's strong sexual, parental, and social instincts give rise to 'do unto others as yourself' and 'love thy neighbor as thyself'.

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

Freedom of thought is best promoted by the gradual illumination of men’s minds which follows from the advance of science.

I look at the natural geological record as a history of the world imperfectly kept and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines.

The more one thinks, the more one feels the hopeless immensity of man's ignorance.

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