It has often been supposed that mediaeval thinkers were in such a sense the creatures of authority that it was impossible for them to exercise any independent judgement; how far this may have been true of the decadent scholasticism of the fourteenth and fifteenth centuries I do not pretend to say, but such a judgement is a ludicrous caricature of the living and active thought of the twelfth and thirteenth centuries, and a little consideration of the critical method which Abelard developed is sufficient to correct this. This is as follows: first some general principle is enunciated for consideration, then all the authorities which may seem to support it are cited, then all the authorities against, and finally the writer delivers his own judgement, criticizing and explaining the opinions which may seem contrary to it. The method has its defects and its limitations, but its characteristic is rather that of scepticism than of credulity. And it is on this method that the most important systems of knowledge of the Middle Ages are constructed. It was applied by Gratian in his _Decretum_, the first great reasoned treatise on Church law, and leads there often to somewhat unexpected conclusions, such as that even the legislative authority of the Pope is limited by the consenting custom of the Christian people;[31] and it is this method upon which the great systematic treatises, like the _Suma Theologica_ of St. Thomas Aquinas, were constructed in the thirteenth century. Whatever its defects may be the method cannot fairly be accused of ignoring difficulties and of a submission to authority which leaves no place for the critical reason. I have, I hope, said enough to make it clear that there was a real and living intellectual movement in the Middle Ages, and that even in those days men had resumed the great adventure of the pursuit of truth. * * * * * We can only for a moment consider the significance and the character of mediaeval civilization as it expresses itself in Art, and we must begin by noticing a distinction between mediaeval art and mediaeval learning, which is of the first importance.