Alas...I too have known love, that ruler of hearts, that soul of our soul: it's never brought me anything except one kiss and twenty kicks in the rump. How could such a beautiful cause produce such an abominable effect on you?
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.
This self-love is the instrument of our preservation; it resembles the provision for the perpetuity of mankind: it is necessary, it is dear to us, it gives us pleasure, and we must conceal it.
Answer me, you who believe that animals are only machines. Has nature arranged for this animal to have all the machinery of feelings only in order for it not to have any at all?
Everything I see about me is sowing the seeds of a revolution that is inevitable, though I shall not have the pleasure of seeing it. The lightning is so close at hand that it will strike at the first chance, and then there will be a pretty uproar. The young are fortunate, for they will see fine things.