"On Health" said: "In March of spring, comb your hair one or two hundred times a day in the morning. When you lie down at night, put a pinch of salt in the hot soup and wash your knees until you lie down, so as to drive away wind and poison beriberi and not stagnate." In other words, combing your hair in the morning in spring and soaking your feet in light salt water at night can promote the circulation of qi and blood, protect health and prevent diseases. Of course, it is ok to soak your feet without salt water. Soaking feet with hot water every night can also promote blood circulation in our body, which is very beneficial to our health.