The word head has two meanings, the first meaning is finger; The second meaning is thinking.
The brain consists of brain, cerebellum, diencephalon and brain stem. Among them, the brain is the highest part of the central nervous system and the main part of the brain. Divided into left and right cerebral hemispheres, the corpus callosum composed of nerve fibers is connected.
The head represents the thought, the ass represents the position, and the interest is behind the position. In other words, interest is the source of motivation, interest drives thoughts, and the head serves the ass, which is a bit interesting. Then ask, why can position and interest determine people's thinking? This seems reasonable, but it still feels a bit narrow and biased, at least the pattern must be small.