The foundation of modern substantive education theory is associative psychology, which comes from the theory of mental state. Associationism or psychoanalysis is the most influential theory, which holds that the mind is a psychological state. British educator Locke and philosopher Hume are pioneers of modern associative psychology. Locke first put forward the word "association". Hume first denied that the mind is an entity. In his view, treating the mind as a spiritual entity is an illusory abstraction formed by people's psychological habits. However, psychological life is a continuation of perception or mental state, and it is a combination of some concepts linked by association. The philosopher D. hartle is the founder of associative psychology. He is a psychological atomist, reducing psychological life to atoms, which produce everything that can be observed in combination. Associative psychology holds that the mind is only a container to accept external impressions and a collection of consciousness or psychological states. Psychological phenomena such as perception, memory, imagination and understanding are all the results of association or combination of various psychological atoms.