"My stars were not Mercury rising in the seventh angle, but Copernicus and Tycho Brahe."

"I have been a mortal, and I have faced my own mortality with courage."

"The celestial machine is not like a divine animal but like a clockwork."

"The heavenly motions are nothing but a continuous song for several voices, perceived not by the ear but by the intellect."

"I confess that I have often erred in my youth, but I have always corrected my errors."