My practicality consists in this, in the knowledge that if you beat your head against the wall it is your head which breaks and not the wall - that is my strength, my only strength.

The larger the island of knowledge, the longer the shoreline of wonder.

It may, however, be said that the level of experience to which concepts are inapplicable cannot yield any knowledge of a universal character, for concepts alone are capable of being socialized.

Inductive reason, which alone makes man master of his environment, is an achievement and when once born it must be reinforced by inhibiting the growth of other modes of knowledge.

Not ignorance, but ignorance of ignorance, is the death of knowledge.