This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...s or services for the products or services of others. And, in this process of trade, a rational man does not seek or desire any more or any less than his own effort can earn. What determines his
earnings? The free market, that is: the voluntary choice and judgment of the men who are willing to trade him their effort in return.
read full book
When a man trades with others, he is counting
— explicitly or implicitly — on their rationality, that is: on their ability to recognize the objective value of his work. (A trade based on any other premise is a con game or a fraud.) Thu...