Keep the faculty of effort alive in you by a little gratuitous exercise every day.

...These healers...my intellect has been unable to assimilate their theories....But their facts are patent and startling; and anything that interferes with the multiplication of such facts, and with our freest opportunity of observing and studying them, will, I believe, be a public calamity.

A good hypothesis in science must have other properties than those of the phenomenon it is immediately invoked to explain, otherwise it is not prolific enough.

In any project the important factor is your belief. Without belief, there can be no successful outcome.

In the deepest heart of all of us there is a corner in which the ultimate mystery of things works sadly.

To study the abnormal is the best way of understanding the normal.

In business for yourself, not by yourself.