But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.
Rene DescartesAt last I will devote myself sincerely and without reservation to the general demolition of my opinions.
Rene DescartesEvery man is indeed bound to do what he can to promote the good of others, and a man who is of no use to anyone is strictly worthless.
Rene DescartesMy third maxim was to try always to conquer myself rather than fortune, and to change my desires rather than the order of the world, and generally to accustom myself to believing that there is nothing entirely in our power except our thoughts, so that after we have done our best regarding things external to us, everything in which we do not succeed is for us absolutely impossible.
Rene Descartes