The value of a commodity, or the quantity of any other commodity for which it will exchange, depends on the relative quantity of labor which is necessary for its production, and not on the greater or less compensation which is paid for that labor.
心理学理论必须通过实践经验的检验。
淡泊平静，忧患就不能影响，邪气就不能侵袭，就德性完备而精神不损。
"Innovation is the lifeblood of any successful business."