So we find that even when scholasticism was most popular in the universities, there were keen-sighted scientists who recommended the modern scientific method of discovering truth. This does not consist in discussing, according to the rules of logic, what a Greek philosopher said hundreds of years ago, but in the patient observation of things about us. * * * * * [Sidenote: Review of the great changes between the break-up of the Roman Empire in the west and the end of the thirteenth century.] We have now traversed somewhat over one half of the long period of fifteen hundred years which separates Europe of to-day from the disintegrating Roman Empire of the fifth century. The eight hundred years which lie between the century of Alaric, Attila, Leo the Great, and Clovis, and that of Innocent III, St. Louis, and Edward I, witnessed momentous changes, quite as important as any that have occurred since. [Sidenote: The 'dark ages.'] It is true that it seemed at first as if the barbarous Goths, Franks, Vandals, and Burgundians were bringing nothing but turmoil and distraction. Even the strong hand of Charlemagne curbed the unruly elements for only a moment; then the discord of his grandsons and the incursions of Northmen, Hungarians, Slavs, and Saracens plunged western Europe once more into the same anarchy and ignorance through which it had passed in the seventh and eighth centuries. Two hundred years and more elapsed after Charlemagne's death before we can begin once more to note signs of progress. While we know little of the eleventh century, and while even its most distinguished writers are forgotten by all save the student of the period, it was undoubtedly a time of preparation for the brilliant twelfth century--for Abelard and St. Bernard, for the lawyers, poets, architects, and philosophers who seem to come suddenly upon the scene. [Sidenote: The twelfth and thirteenth centuries a period of rapid advance.] The Middle Ages may therefore be divided into two fairly distinct and quite different periods. The centuries prior to the age of Gregory VII and of William the Conqueror may, on account of their disorder and ignorance, be properly called the "dark ages," although they beheld some important stages in the transformation of Europe. The later Middle Ages, on the contrary, were a time of rapid and unmistakable progress in almost every line of human endeavor. Indeed by the end of the thirteenth century a great part of those changes were well under way which serve to make modern Europe so different from the condition of western Europe under the Roman Empire. The most striking of these are the following. [Sidenote: Appearance of national states.]