A Fool or a Physician

Can any of your readers inform me who first had the hardihood to enunciate, as his own, the proposition, that "After the age of thirty, a man is either a fool or a physician?" I believe that we owe that saying, as well as the beautiful, though now sadly hackneyed, metaphor of "the parasitical adoration of the rising, and contempt of the setting sun," the one to the shrewd observation, the other to the fancy, of the same mind—that of the imperial Macchiavel, Tiberius —"Let us render unto Cæsar the things that are Cæsar's." —See Tacit. *Ann*. 6.