The knowledge of a great part of the surface of the eastern world was first attained by the conquests made by Alexander. These occurred at a time when the Grecian language and philosophy were so widely spread, that scientific observation and the systematic arrangement of general phenomena, could be rendered most lucid to the mind, and most profitable to the world. By another most providential coincidence, at the moment when an immense store of new materials was thus gathered for study and use, the great Stagirite was at hand to direct inquiry into the facts of natural history, with a comprehensive sagacity never before known. Having explored every possible depth of speculative investigation, and spread out all realms in a map of practical improvement, bounded and defined by definite scientific language, he gave the immense treasure to the West, then just prepared for the donation. Anterior to the Augustan age, science had accumulated many materials, but could hardly be said to exhibit a growing body of determinate results. The Alexandrian school opened on the eastern edge of a new cycle, whose unfolding was manifestly one of great advancement. It was among the Romans that the idea of progressive science was first conceived and declared as a law. Pliny would not despair of seeing proficiency perpetually increased. Seneca, also, felt assured that the time would come when what was now dark would be luminous, and that which is now most admired would be entirely eclipsed by infinitely more resplendent discoveries. Such hopeful sentiments show a confidence of the increase of knowledge, which was not expressed in earlier times. It is especially to be observed that this anticipation, both in Pliny and Seneca, was prompted by the discoveries at that time made in astronomy; which, as Whewell remarks, was "the only progressive science produced by the ancient world." At a later period, Ovid, in the chorus to his Medea, expressed a like confidence in regard to maritime discovery. But the prospect of scientific progress was not connected with much, if any, general improvement of mankind, even in the estimation of those who entertained the fondest expectations. It must, therefore, have afforded some consolation to those who lived when the old world was decomposing, and when its heart, mind and soul, all bore tokens of a great and radical change, to gaze on any bright gleams which science revealed through the clouds of the future.