Princeton University History Department

".if you have a year or two to apply yourself to all that is necessary, I would hope that we might see, by your efforts, if there are animals on the moon." (René Descartes, 1629) With this alluring suggestion, René Descartes invited a young instrument maker to join him on an unprecedented and secret project that promised to revolutionize early modern astronomy. Descartes believed he had conceived a new kind of telescopic lens, ground to the shape of a hyperbola, that wou