Twice in my life I have spent two weary and scientifically profitless years seeking evidence to corroborate dearly loved hypotheses that later proved to be groundless; times such as these are hard for scientists-days of leaden gray skies bringing with them a miserable sense of oppression and inadequacy.

To deride the hope of progress is the ultimate fatuity, the last word in poverty of spirit and meanness of mind.

A scientist is no more a collector and classifier of facts than a historian is a man who complies and classifies a chronology of the dates of great battles and major discoveries.

The Phenomenon of Man stands square in the tradition of Naturphilosophie, a philosophical indoor pastime of German origin which does not seem even by accident (though there is a great deal of it) to have contributed anything of permanent value to the storehouse of human thought.

The attempt to discover and promulgate the truth is nevertheless an obligation upon all scientists, one that must be persevered in no matter what the rebuffs—for otherwise what is the point in being a scientist?

Today the world changes so quickly that in growing up we take leave not just of youth but of the world we were young in.

To abdicate from the rule of reason and substitute for it an authentication of belief by the intentness and degree of conviction with which we hold it can be perilous and destructive. Religious beliefs give a spurious spiritual dimension to tribal enmities.