Then Aristotle, following out the method of his teachers, attempts to exhaust experience, and directs his inquiries into the outward world of sense and observation, but all with the view of discovering from phenomena the unconditional truth, in which he too believes. But everything in this world is fleeting and transitory, and therefore it is not easy to arrive at truth. A cold doubt creeps into the experimental mind of Aristotle, with all his learning and his logic. The Epicureans arise. Misreading or corrupting the purer teaching of their founder, they place their hopes in sensual enjoyment. They despair of truth. But the world will not be abandoned to despair. The Stoics rebuke the impiety which is blended with sensualism, and place their hopes on virtue. Yet it is unattainable virtue, while their God is not a moral governor, but subject to necessity. Thus did those old giants grope about, for they did not know the God who was revealed unto the more spiritual sense of Abraham, Moses, David, and Isaiah. And yet with all their errors they were the greatest benefactors of the ancient world. They gave dignity to intellectual inquiries, while by their lives they set examples of a pure morality. * * * * * The Romans added absolutely nothing to the philosophy of the Greeks. Nor were they much interested in any speculative inquiries. It was only the ethical views of the old sages which had attraction or force to them. They were too material to love pure subjective inquiries. They had conquered the land; they disdained the empire of the air. There were doubtless students of the Greek philosophy among the Romans, perhaps as early as Cato the Censor. But there were only two persons of note in Rome who wrote philosophy, till the time of Cicero,--Aurafanius and Rubinus,--and these were Epicureans.