This is the only book in the literature that describes the complete process of theory construction and testing and its differences from research. Physicists are experts in theory construction but do not write about it, because it looks like ordinary work to them. The reason is that the method of theory construction is built into the human brain/mind by evolution because of its survival value and is used automatically by everyone in daily life. Newton appears to be the first scientist to use this method consciously. He also wrote a few lines about it. A few other physicists too wrote insufficiently about theory construction, whereas the non-physicists who wrote about it made many severe mistakes, as exemplified in this book. It is shown especially that what those non-physicist writers explain as the method of theory construction is in reality the method used in research to obtain empirical knowledge.

Consequently, and despite the fact that the greatest advances in science have been realized by constructing grand theories, many disciplines of science outside Physics are closed to the construction and use of theories. This is true especially concerning Psychology, although the theoretical method is most needed in this discipline because of the nature of mental phenomena. Psychologists even reject the theoretical method as unscientific when someone uses it in Psychology, being also influenced by Freud's failure in constructing a useful grand theory. This attitude has kept Psychology in an immature state with "schools" like philosophy and the arts instead of theories like physics. As applications of the theoretical method, theories are constructed in this book about: primary mental disorders, dreams, migraines, tension headaches, facial neuralgia, and psychotherapy. Research and clinical findings are presented that constitute proofs of the usability of those theories and of the usability of the physicists' method of theory construction in psychology.