The nominalists, on the other hand, argued that "universals" are mere notions of the mind, and that individuals alone are real; their motto was _Universalia sunt nomina_.

Thus the central question in the long controversy concerned the reality of abstract or incorporate ideas, and it is to be observed that the realists held views diametrically opposite to those which the word "realism" today implies.

In upholding the reality of the idea, they were what would now be called idealists, whereas their opponents, denying the reality of abstractions and insisting on that of the concrete individual or object, were realists in the modern sense.
The peculiar importance of this controversy lay in its effect on the status of the Church.

If nominalism should prevail, then the Church would be shorn of much of its authority, for its greatest power lay in the conception of it as an enduring reality outside of and above all the individuals who shared in its work.

It is not strange, then, that the ardent realism of William of Champeaux should have been outraged by the nominalistic logic of Abelard.
Abelard, indeed, never went to such extreme lengths as the arch-nominalist, Roscellinus, who was duly condemned for heresy by the Council of Soissons in 1092, but he went quite far enough to win for himself the undying enmity of the leading realists, who were followed by the great majority of the clergy.
PORPHYRY The Introduction ("Isagoge") to the Categories of Aristotle, Written by the Greek scholar and neoplatonist Porphyry in the third century A.D., was translated into Latin by Boetius, and in this form was extensively used throughout the Middle Ages as a compendium of Aristotelian logic.