Before my time, my teacher had a couple of Tibetan meditation masters. He asked them once if they understood yin and yang. The geshe said of course he did because he had read about it in the books. My teacher told me that that was the point where he lost faith in Tibetan Buddhism. The Dao cannot be understood with the mind, and certainly not by reading about it. It must instead be entered into by stopping the mind and feeling it with the body and particularly in the heart. To know Dao you must become energy.