Kepler quote

Excerpt of a letter from Kepler to Galileo in 1610:

"There will certainly be no lack of human pioneers when we have mastered the art of flight . . . .  Let us create vessels and sails adjusted 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-travellers, maps of the celestial bodies--I shall do it for the moon, you Galileo, for Jupiter."