"Our situation is not so different from that of a donkey with a carrot hanging in front of it. Our carrot is called happiness. When pursuing it, we chase after something we will never obtain. We have the impression that we are born to be happy, but this is only because we are tied to the internal logic of our biological nature. The condition of being alive imposes pleasure and suffering as the supreme points of reference. However, pleasure is only a psychological mechanism designed to influence our behavior, not a reality to which we are heading. This will become clear if we consider the fact that, when we reach the satisfaction of some desire, we have only a few moments of pleasure as a reward and, afterwards, new needs begin to torment us and make us restless. It will not be long before we take action again, in a cycle of dissatisfaction that will only end with the death of the individual or with the acquisition of a grain of good sense."
January 1, 1970
https://en.wikiquote.org/wiki/Philosophical_pessimism