The understanding of using weak Tao against the movement of Tao is that the operation method of Tao is to defeat the strong with the weak; Tao always runs in the opposite direction. The law of Tao is that between the two attributes of things, they always run in the opposite direction, return at the critical point, and so on.

Simple example:

At night, the sun is the weakest, then after dawn, it becomes stronger bit by bit in the morning, reaches the strongest at noon, and then weakens bit by bit, starting from the strongest point, and repeating.

In other words, it returned to its original weak attribute, so that it moved back and forth more than once. Similarly, people's birth, aging, illness and death are also the same changing rules-babies are from soft to weak, middle-aged to strong, then to old age, and return to soft to weak.