“Nature uses as little as possible of anything.”

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

“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]”

“Wer aber soll hausen in jenen Welten, wenn sie bewohnt sein sollten? ... Sind wir oder sie die Herren des Alls? ... Und ist dies alles dem Menschen gemacht?”

“Now because 18 months ago the first dawn, 3 months ago broad daylight but a very few days ago the full sun of the most highly remarkable spectacle has risen — nothing holds me back. I can give myself up to the sacred frenzy, I can have the insolence to make a full confession to mortal men that I have stolen the golden vessel of the Egyptians to make from them a tabernacle for my God far from the confines of the land of Egypt. If you forgive me I shall rejoice; if you are angry, I shall bear it; I am indeed casting the die and writing the book, either for my contemporaries or for posterity to read, it matters not which: let the book await its reader for a hundred years; God himself has waited six thousand years for his work to be seen.”

“The Earth is round, and is inhabited on all sides, is insignificantly small, and is borne through the stars.”