This is a quote from the book "The ​Virtue Of Selfishness" by Ayn Rand
...t upon a mutual trade to mutual benefit.

This is true of all legitimate groups or associations in a free society: partnerships, business concerns, professional associations, labor
unions ( voluntary ones), political parties, etc. It applies also to all agency agreements: the right of one man to act for or represent another or others is derived from the rights of those he represents and is delegated to him by their voluntary choice, for a specific, delimited purpose — as in the case of a lawyer, a business representative, a labor union delegate, etc.
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