The long concatenations of simple and easy reasoning which geometricians use in achieving their most difficult demonstrations gave me occasion to imagine that all matters which may enter the human mind were interrelated in the same fashion.

I think; therefore I am.

Illusory joy is often worth more than genuine sorrow.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

Common sense is the most fairly distributed thing in the world, for each one thinks he is so well-endowed with it that even those who are hardest to satisfy in all other matters are not in the habit of desiring more of it than they already have.

The reading of all good books is like a conversation with the finest minds of past centuries.