Probably, however, the most striking study of the varying qualities of different regions is Giraldus Cambrensis’ elaborate comparison of Orient and Occident.[963] In Chapter VII we discussed this writer’s belief that the atmosphere of the West is far healthier than that of the East. But not only is the air better, he asserted, but also the land itself, and of all the lands Ireland is the most healthy. No venomous reptiles can exist in the Emerald Isle. Giraldus attributed this phenomenon not to the beneficent work of St. Patrick in driving out the snakes[964] (this story, he said, was merely a pleasant fiction) but rather to some natural deficiency in Irish soil that had existed long before St. Patrick’s time. He explained further that no poisonous reptiles could survive in Ireland even when they were brought there;[965] toads, when carried over on ships, burst open as soon as they are thrown ashore; and the dust of Ireland, when sprinkled on poisonous creatures of any sort, kills them instantly.[966] The East, on the other hand, Giraldus called[967] a fountain of poisons (_fons venenorum_), and he waxed most eloquent on its terrors:[968] poisonous animals abound, the waters are always polluted, and death lurks on every hand; but the farther away from this Oriental source of poison one travels, the less its effect, until in the extreme West it exerts no influence at all, just as the sun’s rays are weaker the farther one goes from beneath the zodiac. This distinction between Eastern and Western climate and conditions of terrain may to a limited extent have been based on actual observation. Undoubtedly the pilgrim and Crusader suffered more from disease and hardship when traveling in the Orient than they did at home, because they were not acclimatized to Levantine conditions of life and did not understand what was necessary for the preservation of health; and this may well have produced the unfavorable impression of the East which found its way in exaggerated form into the pages of the _Topographia Hiberniae_. _MOUNTAINS_ Mountains are the most imposing natural features of the lands.[969] Though there did not exist in the Middle Ages anything comparable to that love of mountains for their own sake which developed later and of which we see an early manifestation in the ascent of Mont Ventoux by Petrarch in April, 1336, the very bulk of the hills, nevertheless, impressed men’s imaginations, and medieval literature is full of notices concerning mountains. ORIGIN OF MOUNTAINS