But when we begin to consider another group of men who were to feel the heavy hand of official disapprobation, the scientists, the problem becomes infinitely more complicated. And in order to understand the perverse attitude of the Church authorities towards those who tried to reveal the secrets of nature, we must go back a good many centuries and study what had actually happened in Europe during the first six centuries of our era. The invasion of the Barbarians had swept across the continent with the ruthless thoroughness of a flood. Here and there a few pieces of the old Roman fabric of state had remained standing erect amidst the wastes of the turbulent waters. But the society that had once dwelled within these walls had perished. Their books had been carried away by the waves. Their art lay forgotten in the deep mud of a new ignorance. Their collections, their museums, their laboratories, their slowly accumulated mass of scientific facts, all these had been used to stoke the camp-fires of uncouth savages from the heart of Asia. We possess several catalogues of libraries of the tenth century. Of Greek books (outside of the city of Constantinople, then almost as far removed from central Europe as the Melbourne of today) the people of the west possessed hardly any. It seems incredible, but they had completely disappeared. A few translations (badly done) of a few chapters from the works of Aristotle and Plato were all the scholar of that time could find when he wanted to familiarize himself with the thoughts of the ancients. If he desired to learn their language, there was no one to teach it to him, unless a theological dispute in Byzantium had driven a handful of Greek monks from their customary habitats and had forced them to find a temporary asylum in France or Italy. Latin books there were in great quantity, but most of those dated from the fourth and fifth centuries. The few manuscripts of the classics that survived had been copied so often and so indifferently that their contents were no longer understandable to any one who had not made a life study of paleography. As for books of science, with the possible exception of some of the simplest problems of Euclid, they were no longer to be found in any of the available libraries and what was much more regrettable, they were no longer wanted. For the people who now ruled the world regarded science with a hostile eye and discouraged all independent labor in the field of mathematics, biology and zoology, not to mention medicine and astronomy, which had descended to such a low state of neglect that they were no longer of the slightest practical value. It is exceedingly difficult for a modern mind to understand such a state of affairs. We men and women of the twentieth century, whether rightly or wrongly, profoundly believe in the idea of progress. Whether we ever shall be able to make this world perfect, we do not know. In the meantime we feel it to be our most sacred duty to try.