PROGRESS OF SCIENCE TO 1450 A.D. 173 



Land was, however, the rule until the eleventh century, and 

 between 700 and 1000 A.D. pilgrimages to Jerusalem were fre- 

 quently undertaken by Christians in the West. But after 1010 

 such pilgrimages began to be seriously interfered with, and matters 

 steadily grew worse, until in 1071 Seljukian Turks displaced 

 Arabian Mohammedans as rulers of Jerusalem. These Turks, 

 though more rough than intolerant, eventually interfered with both 

 trade and pilgrimages, until for this and other reasons the conquest 

 of the Holy Land became a passion with the Christian nations. 



In the spring of 1097, after several years of widespread prepara- 

 tion, a great host of western Christians, variously estimated at 

 150,000 to 600,000, gathered at Constantinople charged with war- 

 like and religious zeal and bent on wresting Jerusalem and the 

 Holy Land from the possession of the Mohammedan " Infidel." 

 This was the beginning of those expeditions under the banner of 

 the Cross, hence known as the Crusades, which may be 

 regarded as intermittent reactions of the Christian West against 

 the pressure of the Mohammedan East. The spirit of Christian 

 Europe in the Middle Ages being essentially religious and ec- 

 clesiastical, it was natural that its more bold and adventurous 

 youth should regard with jealousy and indignation the wide 

 extent of the Mohammedan empire and especially its possession 

 of Jerusalem and other holy places. In all, eight such Crusades 

 are recognized by historians, and of these the influence upon 

 Christian Europe must have been immense. In the first place, 

 the expansion of the intellectual outlook due to the mere experiences 

 of travel, for men born and bred under the parochial limitations 

 of feudalism and monasticism, must have been great. Then, too, 

 the arts and appliances observed abroad, the different stand- 

 ards of all sorts, the wealth and luxury of the distant East, doubt- 

 less had a powerful effect upon Europe when reported or intro- 

 duced by the Crusaders upon their return. When we reflect upon 

 the ages of darkness which had rested upon Christian Europe from 

 the fall of Rome into the hands of the barbarians to the fall of 

 Jerusalem into the hands of the Turks a period of almost 

 exactly six hundred years we may agree with those who are 



