This is actually an ancient Chinese saying, but Mao Zedong used it in one of his speeches.
the relevant paragraph:
Physical education not only strengthens the body but also enhances our knowledge. There is a saying: Civilize the mind and make savage the body. This is an apt saying. In order to civilize the mind one must first make savage the body. If the body is made savage, then the civilized mind will follow. Knowledge consists in knowing the things in the world, and in discerning their laws. In this matter we must rely on our body, because direct observation depends on the ears and eyes, and reflection depends on the brain. The ears and eyes, as well as the brain, may be considered parts of the body. When the body is perfect, then knowledge is also perfect. Hence one can say that knowledge is acquired indirectly through physical education. Physical strength is required to undertake the study of the numerous modern sciences, whether in school or through independent study. He who is equal to this is the man with a strong body; he who is not equal to it is the man with a weak body. The division between the strong and the weak determines the area of responsibilities each can assume.
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