The heavenly motions... are nothing but a continuous song for several voices, perceived not by the ear but by the intellect, a figured music which sets landmarks in the immeasurable flow of time.

As soon as somebody demonstrates the art of flying, settlers from our species of man will not be lacking on the moon and Jupiter... Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse.

There will certainly be no lack of human pioneers when we have mastered the art of flight....Let us create vessels and sails justed to the heavenly ether, and there will be plenty of people unafraid of the empty wastes. In the meantime we shall prepare, for the brave sky-travelers, maps of the celestial bodies.

Repudiating the sensible world, which he neither sees himself nor believes from those who have, the Peripatetic joins combat by childish quibbling in a world on paper, and denies the Sun shines because he himself is blind.

The radius vector describes equal areas in equal times.

We do not ask what hope of gain makes a little bird warble, since we know that it takes delight in singing because it is for that very singing that the bird was made, so there is no need to ask why the human mind undertakes such toil in seeking out these secrets of the heavens. ... And just as other animals, and the human body, are sustained by food and drink, so the very spirit of Man, which is something distinct from Man, is nourished, is increased, and in a sense grows up on this diet of knowledge, and is more like the dead than the living if it is touched by no desire for these things.

A mind is accustomed to mathematical deduction, when confronted with the faulty foundations of astrology, resists a long, long time, like an obstinate mule, until compelled by beating and curses to put its foot into that dirty puddle.