"Discover the force of the skies O Men: once recognised it can be put to use."

"If there is anything that can bind the mind of man to this dreary exile of our earthly home and can reconcile us with our fate so that one can enjoy living,—then it is verily the enjoyment of the mathematical sciences and astronomy."

"We ought not to ask why the human mind troubles to fathom the secrets of the universe. The diversity of the phenomena of nature is so great, and the treasures hidden in the skies so rich, precisely in order that the human mind shall never be lacking in fresh nourishment."

"I used to measure the skies, now I measure the shadows of Earth.Although my mind was sky-bound, the shadow of my body lies here.[Epitaph he composed for himself a few months before he died]"

"Geometry has two great treasures; one is the Theorem of Pythagoras; the other, the division of a line into extreme and mean ratio. The first we may compare to a measure of gold; the second we may name a precious jewel."

"Temporis filia veritas; cui me obstetricari non pudet.Truth is the daughter of time, and I feel no shame in being her midwife."

"Priusquam autem ad creationem, hoc est ad finem omnis disputationis, veniamus: tentanda omnia existimo.However, before we come to [special] creation, which puts an end to all discussion: I think we should try everything else."

"Nature uses as little as possible of anything."

"I am much occupied with the investigation of the physical causes [of motions in the Solar System]. My aim in this is to show that the celestial machine is to be likened not to a divine organism but rather to a clockwork ... insofar as nearly all the manifold movements are carried out by means of a single, quite simple magnetic force. This physical conception is to be presented through calculation and geometry."

"So, Fabricius, I already have this: that the most true path of the planet [Mars] is an ellipse, which Dürer also calls an oval, or certainly so close to an ellipse that the difference is insensible."