What are the philosophical principles of "there is no constant force in the army, and water is impermanent" and "this time, another time"?

Therefore, the soldiers are powerless and invisible. Being able to win because of the enemy's change is called God. Sun Tzu said, "Therefore, there is no fixed posture in the use of soldiers, and there is no change in shape ..." Cheng: it is fixed. As the saying goes, "the soldiers have no constant potential, and the water is impermanent." That's what it means. You can't always use a set of combat methods when leading troops to fight. According to the changes in the battlefield situation, the changes in the terrain, and the comparison between the enemy and ourselves, we should formulate operational policies that are in line with objective reality. Otherwise, failure is inevitable and victory is accidental.

Therefore, it embodies its philosophical viewpoint of change and development, and we should look at the problem from the viewpoint of change and development. Second, the contradiction is special and needs specific analysis.