Second, weighing: there are advantages and disadvantages, and whatever has advantages must have disadvantages. We choose through weighing;

Third, master: take and give; Take-return, give-pay, want to take first, pay will be rewarded;

Fourth, epiphany: invariance and change, invariance and change are the unity of opposites. "Invariance" is the universal law of things, "change" is the special law of things, and the universal law often resides in the special law;

Verb (abbreviation of verb) application: square and circle, Fiona Fang generally refers to the shape and character of things, but also refers to methods and norms;

He who sees through: birth and death, life is only a few decades, if it is fleeting, we may not be able to "live great and die glorious", but we must strive to have no regrets and a clear conscience.