In the course of his [General Westmoreland's] testimony, he made the statement that he did not want to command an army of mercenaries. I stopped him and said, 'General, would you rather command an army of slaves?' He drew himself up and said, 'I don't like to hear our patriotic draftees referred to as slaves.' I replied, 'I don't like to hear our patriotic volunteers referred to as mercenaries.' But I went on to say, 'If they are mercenaries, then I, sir, am a mercenary professor, and you, sir, are a mercenary general; we are served by mercenary physicians, we use a mercenary lawyer, and we get our meat from a mercenary butcher.' That was the last that we heard from the general about mercenaries.

Quote in Two Lucky People: Memoirs by Milton and Rose Friedman, Chicago: University of Chicago Press, (1998) p. 380.