Contemplating an object fixedly with the mind, asking myself, 'What is it?' without thinking of any other object or relating it to anything else for hours on end.

Someone who does not see a pane of glass is not aware of not seeing it.

Real genius is nothing else but the supernatural virtue of humility in the domain of thought.

When once a certain class of people has been placed by the temporal and spiritual authorities outside the ranks of those whose life has value, then nothing comes more naturally to men than murder.

When an apprentice gets hurt, or complains of being tired, the workmen and peasants have this fine expression: "It is the trade entering his body." Each time that we have some pain to go through, we can say to ourselves quite truly that it is the universe, the order and beauty of the world, and the obedience of God that are entering our body.

science has now been for a long time - and to an ever-increasing extent - a collective enterprise. Actually, new results are always, in fact, the work of specific individuals; but, save perhaps for rare exceptions, the value of any result depends on such a complex set of interrelations with past discoveries and possible future researches that even the mind of the inventor cannot embrace the whole.

Two forces rule the universe: light and gravity.