Everyone has a theory of human nature. Everyone has to anticipate the behavior of others, and that means we all need theories about what makes people… - Tom Butler-Bowdon

Unpleasant feelings merely indicate that you are thinking something negative and believing it.

49 Wilhelm Wundt Principles of Physiological Psychology (1873–74) The book that made Wundt the dominant figure in the new science of psychology. Translated into English by Edward Titchener in 1904.

Ever more patients complain of a feeling of emptiness and meaninglessness, which seems to derive from two facts. Unlike an animal, man is not told by instincts what he must do. And unlike man in former times, he is no longer told by traditions what he should do. Often he does not even know what he basically wishes to do. Instead, he either wishes to do what other people do (conformism), or he does what other people wish him to do (totalitarianism).