To expect a man to retain everything that he has ever read is like expecting him to carry about in his body everything that he has ever eaten.

Physics is unable to stand on its own feet, but needs a metaphysics on which to support itself, whatever fine airs it may assume towards the latter.

It is only in the microscope that our life looks so big. It is an indivisible point, drawn out and magnified by the powerful lenses of Time and Space.

There is no absurdity so palpable but that it may be firmly planted in the human head if you only begin to inculcate it before the age of five, by constantly repeating it with an air of great solemnity.

At bottom, every state regards another as a gang of robbers who will fall upon it as soon as there is an opportunity.

A man who has not enough originality to think out a new title for his book will be much less capable of giving it new contents.

One can never read too little of bad, or too much of good books: bad books are intellectual poison; they destroy the mind. In order to read what is good one must make it a condition never to read what is bad; for life is short, and both time and strength limited.