The focus of the article is the self-predication principle, according to which the/a such-and-such is such-and-such. We consider contemporary approaches (Frege, Russell, Meinong) to the self-predication principle, as well as fourteenth-century approaches (Burley, Ockham, Buridan). The Ockham-Buridan view prefigures, in crucial ways, Russell's view, and Burley’s view shows a striking resemblance to Meinong's view. In a slogan, the Russell-Ockham-Buridan view holds: no existence, no truth. In a slogan, the Buridan-Meinong view holds: intelligibility suffices for truth. Both views approach self-predication in an uniform way. We did not find a medieval philosopher who, like Frege, approaches self-predication in a non-uniform way. We do not want...