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.
The wicked can have only accomplices, the voluptuous have companions in debauchery, self-seekers have associates, the politic assemble the factions, the typical idler has connections, princes have courtiers. Only the virtuous have friends.
I have lived eighty years of life and know nothing for it, but to be resigned and tell myself that flies are born to be eaten by spiders and man to be devoured by sorrow.
I have wanted to kill myself a hundred times, but somehow I am still in love with life. This ridiculous weakness is perhaps one of our more stupid melancholy propensities, for is there anything more stupid than to be eager to go on carrying a burden which one would gladly throw away, to loathe one’s very being and yet to hold it fast, to fondle the snake that devours us until it has eaten our hearts away?
Ask a toad what is beauty....; he will answer that it is a female with two great round eyes coming out of her little head, a large flat head, a yellow belly and a brown back.
The instruction we find in books is like fire. We fetch it from our neighbours, kindle it at home, communicate it to others, and it becomes the property of all.