"Illusory joy is often worth more than genuine sorrow." — Rene Descartes

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.

Perfect numbers like perfect men are very rare.

One cannot conceive anything so strange and so implausible that it has not already been said by one philosopher or another.