The prevailing tendency to regard all the marked distinctions of human character as innate, and in the main indelible, and to ignore the irresistible proofs that by far the greater part of those differences, whether between individuals, races, or sexes are such as not only might but naturally would be produced by differences in circumstances, is one of the chief hinderances to the rational treatment of great social questions, and one of the greatest stumbling blocks to human improvement.

The world would be astonished if it knew how great a proportion of its brightest ornaments, of those distinguished even in popular estimation for wisdom and virtue, are complete sceptics in religion.

The application of algebra to geometry ... has immortalized the name of Descartes, and constitutes the greatest single step ever made in the progress of the exact sciences.

I have observed that not the man who hopes when others despair, but the man who despairs when others hope, is admired by a large class of persons as a sage.

... the besetting danger is not so much of embracing falsehood for truth, as of mistaking a part of the truth for the whole.

No one can be a great thinker who does not recognize that as a thinker it is his first duty to follow his intellect to whatever conclusions it may lead.

Pleasure and freedom from pain, are the only things desirable as ends.