While the clouds that befogged the study of medicine in the Empire of the East thus grew heavier and heavier, we must not be blind to the melancholy spectacle concerning the provinces composing the Empire of the West. Barbarians in swarms, from the forests of Germany and Scandinavia, had swept its various portions, pillaging, destroying, and reducing to slavery its inhabitants. In southern Europe everything was changed. Each generation witnessed some new and unheard-of invader, who demanded his share of booty and renown and left a track of desolation behind him. There was a brief period of order when Charlemagne reunited under one dominion these divers races and seemed to have resuscitated the Western Empire; but no sooner was he dead than its elements, being devoid of affinity, broke apart. Former vassals, no longer restrained by the firm hand of the emperor, made common warfare against his successors and against each other, and for several ages there was nothing but a succession of wars and invasions. Feudalism gave some sort of character to this military anarchy by affording repose and, in a measure, security for those who had hitherto been trampled under foot; but learning and the sciences fell into complete neglect, and it was with great difficulty that a very small number of men found within the pale of the church a limited protection that enabled them to devote themselves to the study of medicine and ecclesiastical law. Near the end of the eleventh century, however, the enthusiasm of the crusades whetted anew the turbulent appetite of the Christian barons, and led these lords of western Europe, with their belligerent spirits, to the East, as a result of which people hitherto oppressed could breathe more freely. A few States recovered their{068} independence; some semblance of law was established; municipal institutions were organized, and establishments consecrated to public use were founded and multiplied; finally, in the course of the thirteenth and fourteenth centuries, the cloud which covered the face of Roman Catholic Europe was in some measure dispersed, and men of talent and even genius began to appear upon the scene; everything about them being so obscure, they shone like stars in the firmament. In letters, for instance, there were Dante, Petrarch, Boccaccio; in mathematics, Leonard, of Pisa, the first in Europe to understand and employ figures and algebraic characters, although Cuvier has claimed this distinction for Gerbert, a Benedictine monk of the tenth century, who subsequently became Pope Sylvester II. At this time, although in scholastic estimation medicine, theology, and philosophy alone were fit to entertain the human mind, the natural sciences were not without occasional representatives. Roger Bacon was three centuries in advance of scientific reform, and endeavored to introduce experimental philosophy, and so fully convinced some of his auditors that they subscribed £2000 sterling to provide for the expense of