 Like Walter Burley and Wyclif, Penbygull holds that such formal universals exist in act (in actu) outside our minds, and not in potency (in potentia) only, as moderate realists (like St. Thomas Aquinas) thought, since for Penbygull the necessary and sufficient condition that a thing must meet for being a universal is the existence of at least one individual in which it is present (De universalibus, p. 178). So the actual existence of universals depends entirely on that of their individuals; without them, common natures could not be really universals.