Bad books engender bad habits, but bad habits engender good books.

The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.

Just as we believe by faith that the greatest happiness of the next life consists simply in the contemplation of this divine majesty, likewise we experience that we derive the greatest joy of which we are capable in this life from the same contemplation, even though it is much less perfect.

The chief cause of human errors is to be found in the prejudices picked up in childhood.

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.

The only thing that I know, is that I know nothing

How can you be certain that your whole life is not a dream?