We must be skeptical even of our skepticism.

Dogmatism and skepticism are both, in a sense, absolute philosophies; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or ignorance.

A drop of water is not immortal; it can be resolved into oxygen and hydrogen. If, therefore, a drop of water were to maintain that it had a quality of aqueousness which would survive its dissolution we should be inclined to be skeptical. In like manner we know that the brain is not immortal.

Science is no substitute for virtue; the heart is as necessary for a good life as the head.

The scientific attitude of mind involves a sweeping away of all other desires in the interest of the desire to know.

Tobacco . . . is not prohibited in the Scriptures, though, as Samuel Butler points out, St. Paul would no doubt have denounced it if he had known of it.

Right discipline consists, not in external compulsion, but in the habits of mind which lead spontaneously to desirable rather than undesirable activities.