The intellectual activity of the schoolmen was connected mainly with questions of interpretation. Original investigation was scarcely attempted. The form adopted was that of commenting upon Aristotle or the Church Fathers, and the method employed was that of discussion and dispute, conducted according to recognised logical methods. At an early date, a question which was considered of primary and fundamental significance began to be discussed--the nature of universals. Stated briefly, the problem is: have the universals a substantial existence of their own, as the realists claimed, or, are they merely conceptions in the mind, as the nominalists maintained? This philosophical problem was bound up with such questions as the reality of the Church, of the State, of the Trinity, of the Sacraments. Was the Church a "reality," or was it merely the name of certain individuals who professed a certain allegiance? Was the State a "reality," or simply a name? Such questions as these serve to illustrate the passionate interest taken in the matter by the medieval world of learning. It was under the stimulus of this interest in dialectic that certain schools connected with cathedrals or monasteries became famous in the later eleventh century and the beginning of the twelfth. Prominent among these was Paris, as the reputation of its master, William of Champeaux, attracted scholars to it from many parts. Abelard was one of the students who had been drawn to Paris by the fame of its school, but before long he openly combatted the teachings of its masters and determined to open school for himself. On account of the principle of the licensing of schools and of teachers, this was a matter difficult of accomplishment, but the difficulties were temporarily overcome, and Abelard is later found as the deputy master of the Cathedral School. Fresh difficulties arising, Abelard resumed his studies, this time under Anselm at Laon. Later he returned to Paris, and lectured as a duly authorised master in the schools of Notre-Dame. His reputation spread rapidly, and Abelard became supreme in the intellectual capital of Europe. In 1118 occurred his rapid and terrible downfall occasioned by his liaison with Heloise. In every attempt which he made after this to regain his position, he was met by fierce and relentless opposition especially from Bernard of Clairvaux. Twice he was condemned for heresy, in 1121 and 1141; his persecution being due, not so much to definite heretical opinions as to the general spirit and method of his teaching. Abelard may be regarded as the best exponent of his time of that method which applies the test of reason to all established beliefs and opinions. Though he was defeated personally at the Council of Sens, yet the movement which had been associated with his name continued.