The facts which have caused us to believe in the dominance of the pleasure principle in mental life also find expression in the hypothesis that the mental apparatus endeavours to keep the quantity of excitation present in it as low as possible or at least to keep it constant.

It is unreasonable to expect science to produce a system of ethics-ethics are a kind of highway code for traffic among mankind-and the fact that in physics atoms which were yesterday assumed to be square are now assumed to be round is exploited with unjustified tendentiousness by all who are hungry for faith; so long as physics extends our dominion over nature, these changes ought to be a matter of complete indifference to you.

Religious doctrines … are all illusions, they do not admit of proof, and no one can be compelled to consider them as true or to believe in them.

Every man has a right over his own life and war destroys lives that were full of promise; it forces the individual into situations that shame his manhood, obliging him to murder fellow men, against his will.

A man like me cannot live without a hobby-horse, a consuming passion - in Schiller's words a tyrant. I have found my tyrant, and in his service I know no limits. My tyrant is psychology. It has always been my distant, beckoning goal and now since I have hit upon the neuroses, it has come so much the nearer.

A father's death is the most important event, the more heartbreaking and poignant loss in a man's life.

Smoking is indispensable if one has nothing to kiss.