The spirit of God, like the sun, always gives all its light at once. The spirit of man resembles the pale moon, which has its phases, its absences and its returns, its lucidity and its spots, its fullness and its disappearance, which borrows all its light from the rays of the sun, and which still dares to intercept them on occasion.

Because a fact seems strange to you, you conclude that it is not one. ... All science, however, commences by being strange. Science is successive. It goes from one wonder to another. It mounts by a ladder. The science of to-day would seem extravagant to the science of a former time. Ptolemy would believe Newton mad.

...mothers are often fondest of the child which has caused them the greatest pain.

A stand can be made against invasion by an army; no stand can be made against invasion by an idea.

If I were Jesus Christ, I would save Judas.

Genius is rare because the means of becoming one have not been available

A language does not become fixed. The human intellect is always on the march, or, if you prefer, in movement, and languages with it.