《孙膑兵法·奇正》
天地间万事万物变化演进的道理是：物极必反，盛极必衰，朝代的兴衰替代，就如同一年四季的变化交替一般，是正常而必然的现象。
天地之理，至则反，盈则败，日月是也。代兴代废，四时是也。
The principle of the evolution and change of all things between heaven and earth is: extremes will reverse, prosperity will decline. The rise and fall of dynasties, just like the change of seasons, is a normal and inevitable phenomenon.