It's common as dirt. You quote Plato, Aristotle, Ovid, and other Grecoroman philosophers all the time, and you don't even know it. Not to mention Shakespeare,

It's common as dirt. You quote Plato, Aristotle, Ovid, and other Grecoroman philosophers all the time, and you don't even know it. Not to mention Shakespeare, Aesop, and even modern day people. (Inspiration vs perspiration, for example.) Many "sayings" have origins with a specific person who said or wrote it, in a documented fashion, even though they've slipped into common culture. Even new words, like "OK" and "bloodstained." If people really want to bitch about David that much, there are much, much better grounds they can find than this.