Master and servant are names as old as history, but given to those of far different condition; for a freeman makes himself a servant to another, by selling him, for a certain time, the service he undertakes to do, in exchange for wages he is to receive: and though this commonly puts him into the family of his master, and under the ordinary discipline thereof; yet it gives the master but a temporary power over him, and no greater than what is contained in the contract between them.