Philosophy in the time of Seneca was a very different thing from the great cosmic systems of Ionia and Magna Graecia, or even from the system of the older Stoicism. Speculative interest had long before his time given way to the study of moral problems with a definite practical aim. If the stimulus of the searching method of Socrates gave an impetus for a century to abstract speculation, it had an even more decided and long-lived influence in diverting thought to moral questions from the old ambitious paths. His disciples Antisthenes and Aristippus prepared the way for the Stoic and Epicurean schools which dominated the Roman world in the last century of the Republic and the first of the Empire. And even Plato and Aristotle indirectly helped forward the movement. It is not merely that, for both these great spirits, the cultivation of character and the reform of society have a profound interest. But even in their metaphysics, they were paving the way for the more introspective and practical turn which was taken by post-Aristotelian philosophy, by giving to what were mere conceptions of the mind a more real existence than to the things of sense.(1571) The “ideas” or “forms” which they contrast with the world of concrete things, are really creations of the individual mind of which the reality must be sought in the depths of consciousness, however they may be divinised and elevated to some transcendental region beyond the limits of sense and time. With Aristotle, as with Plato, in the last resort, the higher reason is the true essence of man, coming into the body from a diviner world, and capable of lifting itself to the ideal from the cramping limitations of sensuous life. The philosopher in the _Phaedo_ who turns his gaze persistently from the confusing phantasmagoria of the senses to that realm of real existence, eternal and immutable, of which he has once had a vision, is really the distant progenitor of the sage of Stoicism, who cuts himself off from the external objects of desire, to find within a higher law, and the peace which springs from a life in harmony with the Reason of the world.