Conscience is the internal perception of the rejection of a particular wish operating within us.

Dreams are constructed from the residue of yesterday.

Cigars served me for precisely fifty years as protection and a weapon in the combat of life... I owe to the cigar a great intensification of my capacity to work and a facilitation of my self-control.

The more the fruits of knowledge become accessible to men, the more widespread is the decline of religious belief.

The whole life of instinct serves the one end of bringing about death.

Indeed, the great Leonardo (da Vinci) remained like a child for the whole of his life in more than one way. It is said that all great men are bound to retain some infantile part. Even as an adult he continued to play, and this was another reason why he often appeared uncanny and incomprehensible to his contemporaries.

The price we pay for our advance in civilization is a loss of happiness through the heightening of the sense of guilt.