De parasito sive artem esse parasiticam

Lucian of Samosata

Lucian, Vol. 3. Harmon, A. M., editor. London: William Heinemann, Ltd.; Cambridge, MA: Harvard University Press, 1921.

Again, there is nothing to hinder a rhetorician or a geometer or a blacksmith from working at his trade whether he is a knave or a fool, but nobody can be a parasite who is either a knave or a fool.

TYCHIADES Goodness! What a fine thing you make out Parasitic to be! I myself already want to be a parasite, I think, rather than what I am.