Humanity is in the highest degree irrational, so that there is no prospect of influencing it by reasonable arguments. Against prejudice one can do nothing.

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.

We should picture the instrument that carries our mental functioning as resembling a compound microscope or photographic apparatus.

There is a powerful force within us, an un-illuminated part of the mind - separate from the conscious mind that is constantly at work molding our thought, feelings, and actions.

We may insist as often as we like that man's intellect is powerless in comparison to his instinctual life, and we may be right in this. Nevertheless, there is something peculiar about this weakness. The voice of the intellect is a soft one, but it will not rest until it has gained a hearing. Finally, after a countless succession of rebuffs, it succeeds.

The functional importance of the ego is manifested in the fact that normally control over the approaches to motility devolves upon it. Thus in its relation to the id it is like a man on horse back, who has to hold in check the superior strength of the horse; with this difference, that the rider tries to do so with his own strength while the ego uses borrowed forces.

In the theory of psycho-analysis we have no hesitation in assuming that the course taken by mental events is automatically regulated by the pleasure principle. We believe, that is to say, that the course of those events is invariably set in motion by an unpleasurable tension, and that it takes a direction such that its final outcome coincides with a lowering of that tension that is, with an avoidance of unpleasure or a production of pleasure.