Religion is an illusion and it derives its strength from the fact that it falls in with our instinctual desires.

Dogs love their friends and bite their enemies, quite unlike people, who are incapable of pure love and always have to mix love and hate.

I was making frequent use of cocaine at that time ... I had been the first to recommend the use of cocaine, in 1885, and this recommendation had brought serious reproaches down on me.

If all the evidence put forward for the authenticity of religious teachings originates in the past, it is natural to look round and see whether the present, about which it is easier to form judgements, may not also be able to furnish evidence of the sort. If by this means we could succeed in clearing even a single portion of the religious system from doubt, the whole of it would gain enormously in credibility.

My boy! Smoking is one of the greatest and cheapest enjoyments in life, and if you decide in advance not to smoke, i can only feel sorry for you.

This is one race of people for whom psychoanalysis is of no use whatsoever.

By abolishing private property one deprives the human love of aggression.