The indestructibility of freethought, meanwhile, was being proved even in the philosophic schools, under all their conformities to faith. Already in the ninth century we have seen Scotus Erigena putting the faith in jeopardy by his philosophic defence of it. Another thinker, Roscelin (or Roussellin: fl. 1090), is interesting as having made a critical approach to freethought in religion by way of abstract philosophy. With him definitely begins the long academic debate between the Nominalists and Realists so called. In an undefined way, it had existed as early as the ninth century, [1362] the ground being the Christian adoption of Plato's doctrine of ideas--that individual objects are instances or images of an ideal universal, which is a real existence, and prior to the individual thing: "universalia ante rem." To that proposition Aristotle had opposed the doctrine that the universal is immanent in the thing--"universalia in re"--the latter alone being matter of knowledge; [1363] and in the Middle Ages those who called Aristotle master carried his negation of Plato to the extent of insisting that the "universal" or "abstract," or the "form" or "species," is a mere subjective creation, a name, having no real existence. This, the Nominalist position--mistakenly ascribed to Aristotle [1364]--was ultimately expressed in the formula, "universalia post rem." Such reasonings obviously tend to implicate theology; and Roscelin was either led or helped by his Nominalist training to deny either explicitly or implicitly the unity of the Trinity, arguing in effect that, as only individuals are real existences, the actuality of the persons of the Trinity involves their disunity. [1365] The thesis, of course, evoked a storm, the English Archbishop Anselm and others producing indignant answers. Of Roscelin's writing only one letter is extant; and even Anselm, in criticizing his alleged doctrine, admits having gathered it only from his opponents, whose language suggests perversion. [1366] But if the testimony of his pupil Abailard be truthful, [1367] he was at best a confused reasoner; and in his theology he got no further than tritheism, then called ditheism. [1368] Thus, though "Nominalism, by denying any objective reality to general notions, led the way directly to the testimony of the senses and the conclusions of experience," [1369] it did so on lines fatally subordinate to the theology it sought to correct. Roscelin's thesis logically led to the denial not only of trinity-in-unity but of the Incarnation and transubstantiation; yet neither he nor his opponents seem to have thought even of the last consequence, he having in fact no consciously heretical intention. Commanded to recant by the Council of Soissons in 1092, he did so, and resumed his teaching as before; whereafter he was ordered to leave France. Coming to England, he showed himself so little of a rebel to the papacy as to contend strongly for