After eliminating all the sources of misery due to folly and vice, Epicurus had still to deal with what, in his opinion, were the most formidable obstacles to human happiness, dread of the divine anger and dread of death, either in itself, or as the entrance on another life. To meet these, he compiled, for we can hardly say constructed, an elaborate system of physical philosophy, having for its object to show that Nature is entirely governed by mechanical causes, and that the soul perishes with the body. We have already mentioned that for science as such and apart from its ethical applications he neither cared nor pretended to care in the least. It seems, therefore, rather surprising that he could not manage, like the Sceptics before him, to get rid of supernaturalism by a somewhat more expeditious method. The explanation seems to be that to give some account of natural phenomena had become, in his time, a necessity for every one aspiring to found a philosophical system. A brilliant example had been set by Plato and Aristotle, of whom the former, too, had apparently yielded to the popular demand rather than followed the bent of his own genius, in turning aside from ethics to physics; and Zeno had similarly included the whole of knowledge in his teaching. The old Greek curiosity respecting the causes of things was still alive; and a similar curiosity was doubtless awakening among those populations to whom Greek civilisation had been carried by colonisation, commerce, and conquest. Now, those scientific speculations are always the most popular which can be shown to have some bearing on religious belief, either in the way of confirmation or of opposition, according as faith or doubt happens to be most in the ascendent. Fifty years ago, among ourselves, no work on natural philosophy could hope for a large circulation unless it was filled with teleological applications. At present, liberal opinions are gaining ground; and those treatises are most eagerly studied which tend to prove that everything in Nature can be best explained through the agency of mechanical causation. At neither period is it the facts themselves which have excited most attention, but their possible bearing on our own interests. Among the contemporaries of Epicurus, the two currents of thought that in more recent times have enjoyed an alternate triumph, seem to have co-existed as forces of about equal strength. The old superstitions were rejected by all thinking men; and the only question was by what new faith they should be replaced. Poets and philosophers had alike laboured to bring about a religious reformation by exhibiting the popular mythology in its grotesque deformity, and by constructing systems in which pure monotheism was more or less distinctly proclaimed. But it suited the purpose, perhaps it gratified the vanity of Epicurus to talk as if the work of deliverance still remained to be done, as if men were still