When a man tells you that he knows the exact truth about anything you are safe in inferring that he is an inexact man.

Although this may seem a paradox, all exact science is based on the idea of approximation. If a man tells you he knows a thing exactly, then you can be safe in inferring that you are speaking to an inexact man.

Insight, untested and unsupported, is an uncertain guarantee of the truth.

There is much pleasure to be gained from useless knowledge.

To avoid the various foolish opinions to which mankind are prone, no superhuman genius is required. A few simple rules will keep you, not from all error, but from silly error.

Philosophy, though unable to tell us with certainty what is the true answer to the doubts which it raises, is able to suggest many possiblities which enlarge our thoughts and free them from the tyranny of custom. Thus, while diminishing our feeling of certainty as to what things are, it greatly increases our knowledge as to what the may be; it removes the somewhat arrogant dogmatism of those who have never travelled into the region of liberating doubt, and it keeps alive our sense of wonder by showing familar things in an unfamilar aspect

The world that I should wish to see would be one freed from the virulence of group hostilities and capable of realizing that happiness for all is to be derived rather from co-operation than from strife. I should wish to see a world in which education aimed at mental freedom rather than imprisoning the minds of the young in rigid armor of dogma calculated to protect them through life against the shafts of impartial evidence.