The men of experiment are like the ant; they only collect and use. But the bee...gathers its materials from the flowers of the garden and of the field, but transforms and digests it by a power of its own.

Vows begin when hope dies.

King of the animals — as thou hast described him — I should rather say king of the beasts, thou being the greatest — because thou hast spared slaying them, in order that they may give thee their children for the benefit of the gullet, of which thou hast attempted to make a sepulchre for all animals; and I would say still more, if it were allowed me to speak the entire truth.

I say that the power of vision extends through the visual rays to the surface of non-transparent bodies, while the power possessed by these bodies extends to the power of vision.

O speculators about perpetual motion, how many vain chimeras have you created in the like quest? Go and take your place with the seekers after gold.

The merit of painting lies in the exactness of reproduction. Painting is a science and all sciences are based on mathematics. No human inquiry can be a science unless it pursues its path through mathematical exposition and demonstration.

Details make perfection, and perfection is not a detail.