Descartes constructed as noble a road of science, from the point at which he found geometry to that to which he carried it, as Newton himself did after him. ... He carried this spirit of geometry and invention into optics, which under him became a completely new art.
It is amusing that a virtue is made of the vice of chastity; and it's a pretty odd sort of chastity at that, which leads men straight into the sin of Onan, and girls to the waning of their color.