A doctor who doesn't say too many foolish things is a patient half-cured. (1921)

A fool must now and then be right, by chance

Any man who does not make himself proficient in at least two languages other than his own is a fool.

Examinations are formidable even to the best prepared, for the greatest fool may ask more than the wisest man can answer.

Experience of actual fact either teaches fools or abolishes them.

Heraldry has been contemptuously termed 'the science of fools with long memories.'

In reality, all arguments from experience are founded on the similarity which we discover among natural objects, and by which we are induced to expect effects similar to those which we have found to follow from such objects. And though none but a fool or madman will ever pretend to dispute the authority of experience, or to reject that great guide of human life, it may surely be allowed a philosopher to have so much curiosity at least as to examine the principle of human nature, which gives this mighty authority to experience, and makes us draw advantage from that similarity which nature has placed among different objects. From causes which appear similar we expect similar effects. This is the sum of our experimental conclusions.

Science is a way to not fool ourselves.

There are no foolish questions and no man becomes a fool until he has stopped asking questions.