Yet in attempting to estimate the debt of the West to the Crusades it should be remembered that many of the new things may well have come from Constantinople, or through the Saracens of Sicily and Spain, quite independently of the armed incursions into Syria.[132] Moreover, during the twelfth and thirteenth centuries towns were rapidly growing up in Europe, trade and manufactures were extending, and the universities were being founded. It would be absurd to suppose that without the Crusades this progress would not have taken place. So we may conclude that the distant expeditions and the contact with strange and more highly civilized peoples did no more than hasten the improvement which was already perceptible before Urban made his ever-memorable address at Clermont.[133] General Reading.--A somewhat fuller account of the Crusades will be found in EMERTON, _Mediæval Europe_, Chapter XI. Their results are discussed in ADAMS, _Civilization_, Chapter XI. Professor Munro has published a number of very interesting documents in _Translations and Reprints_, Vol. I, Nos. 2, 4 (Letters of the Crusaders), and Vol. III, No. 1 (The Fourth Crusade). See also his _Mediæval History_, Chapter XI, on the Crusades. ARCHER and KINGSFORD, _The Crusades_ (G.P. Putnam's Sons, $1.50), is probably the best modern work in English. CHAPTER XVI THE MEDIÆVAL CHURCH AT ITS HEIGHT 78. In the preceding pages it has been necessary to refer constantly to the Church and the clergy. Indeed, without them mediæval history would become almost a blank, for the Church was incomparably the most important institution of the time and its officers were the soul of nearly every great enterprise. In the earlier chapters, the rise of the Church and of its head, the pope, has been reviewed, as well as the work of the monks as they spread over Europe. We must now consider the mediæval Church as a completed institution at the height of its power in the twelfth and thirteenth centuries. [Sidenote: Ways in which the mediæval church differed from modern churches.] We have already had abundant proofs that the mediæval Church was very different from modern churches, whether Catholic or Protestant. [Sidenote: Membership in the mediæval church compulsory.] 1. In the first place, every one was required to belong to it, just as we all must belong to the state to-day. One was not born into the Church, it is true, but he was ordinarily baptized into it before he had any opinion in the matter. All western Europe formed a single religious association, from which it was a crime to revolt. To refuse allegiance to the Church, or to question its authority or teachings, was reputed treason against God and was punishable with death. [Sidenote: The wealth of the Church.] [Sidenote: The tithe.]