Literature is perhaps nowadays the most characteristic expression of civilization, just as painting was the most striking mode of expression in the Renaissance and architecture in the Middle Ages. We have seen that, in the Netherlands, civic monuments constitute a typical feature in mediaeval architecture, but, though it is important to insist on the conditions which favoured and inspired the building of belfries and cloth-halls, the important part played by churches in the Netherlands, as in France and England, must nevertheless be acknowledged. It is true that, considering the intense religious life of the Low Countries from the tenth to the fifteenth centuries, the number of well preserved old churches still existing is rather disappointing, but this impression would be greatly altered if it were possible to revive the buildings which have fallen victim to destruction or to a worse fate still, wholesale restoration. [_SECOND CRUSADE_] All through the Middle Ages, Belgium was an extraordinarily active centre of religious teaching and mysticism, and nowhere else perhaps in Europe did the Christian faith penetrate so deeply among the common people. Quite apart from the intellectual and aristocratic movements favoured in the tenth and eleventh centuries by the imperial bishops of Liege and their celebrated schools, from the deeper influence exerted in other parts by the Clunisian monks (eleventh century) and by the Cistercians and Premontres (twelfth century), the enthusiasm aroused by the crusades is a sufficient proof of the country's religious fervour. Not only did the nobles play a predominant part, Godfrey of Bouillon, Duke of Lower Lotharingia, being the leader of the first crusade and the counts of Flanders, Robert II, Thierry of Alsace, Philip of Alsace and Baldwin IX, taking a large share in the same and in subsequent expeditions, but the lower classes enlisted with the same enthusiasm and flocked around the cross raised by Peter the Hermit and his followers. It is reported that, during the second crusade, certain localities lost more than half their male population. Later, with the development of the Communes, the bourgeois and the townspeople endeavoured to nominate their own priests and chaplains, civil hospitals were founded, and, in the thirteenth century, the mendicant orders enjoyed an enormous popularity, owing to the familiarity with which they mixed with the people. They followed the armies in the field, and it was among them that the citizens found their favourite preachers in times of peace.