380 THE HISTORY OF MEDIEVAL EUROPE individual actions are just. Again, men differ in complexion, size, and temperament; is there any human genus and species which includes them all, or any ideal man after whom they are all patterned? Or, is humanity a mere collective word or simply a conception attained by our minds? Such was the problem of universals agitating the dialecticians when Abelard began his education. Those who regarded such abstract and collective terms as mere names were called "Nominalists." Those who held them to be true sub- stances, although perhaps substances of an incorporeal and spiritual nature, were called "Realists." Those who, like Abelard himself, took a middle course, were called "Con- ceptualists." All this discussion was a distant echo and revival of the theory of ideas, in which Plato, fifteen hun- dred years before in the Academy at Athens, had instructed Aristotle and his other disciples, and which is still reflected in modern idealism. The theory of spiritual substances was very welcome to the Christian thinkers of the Middle Ages, since it con- Relation of fi rme d their belief in a human soul separate from dialectic to the mortal body and in a host of demons and angels. That substance was something distinct from external appearance and particular qualities was also an attractive thought to them. It enabled them to explain that in the sacrament of the mass, while the bread and wine might retain their outward qualities such as are appar- ent to the senses of sight, taste, and touch, yet their inner nature had been "transubstantiated" into the body and blood of Christ. This illustrates what important bearings logic or dialectic might have upon theology. Abelard himself soon gave up teaching for a time in order to study theology at Laon with a master called Anselm. Abelard as This was not, however, the famous Anselm, a theologian Archbishop of Canterbury under William Rufus and Henry I, who put forth the ontological argument for the existence of God. Abelard, who formerly had made his teachers in logic a deal of trouble by frequently disagreeing and arguing with them, now soon became disgusted with