This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...fit from the knowledge discovered by others. The second great benefit is the division of labor: it enables a man to devote his effort to a particular field of work and to trade with others who s
pecialize in other fields. This form of cooperation allows all men who take part in it to achieve a greater knowledge, skill and productive return on their effort than they could achieve if each
had to produce everything he needs, on a desert island or on a self-sustaining farm.
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“But these very benefits indicate, delimit and define what kind of men can be of value to on...