Plato is much more interested in the moral sciences than in the physical, but he, nevertheless, feels called upon to give an account of how the world was made and out of what sort of elements.  He evidently does not take his own account very seriously, and recognizes that he is on uncertain ground.  But he does not consider the matter beyond his jurisdiction.

As for Aristotle, that wonderful man seems to have found it possible to represent worthily every science known to his time, and to have marked out several new fields for his successors to cultivate.  His philosophy covers physics, cosmology, zooelogy, logic, metaphysics, ethics, psychology, politics and economics, rhetoric and poetics.

Thus we see that the task of the philosopher was much the same at the period of the highest development of the Greek philosophy that it had been earlier.  He was supposed to give an account of the system of things.  But the notion of what it means to give an account of the system of things had necessarily undergone some change.  The philosopher had to be something more than a natural philosopher.

3.  Philosophy as A guide to life.—­At the close of the fourth century before Christ there arose the schools of the Stoics, the Epicureans, and the Skeptics.  In them we seem to find a somewhat new conception of philosophy—­philosophy appears as chiefly a guide to life.  The Stoic emphasizes the necessity of living “according to nature,” and dwells upon the character of the wise man; the Epicurean furnishes certain selfish maxims for getting through life as pleasantly as possible; the Skeptic counsels apathy, an indifference to all things,—­blessed is he who expects nothing, for he shall not be disappointed.

And yet, when we examine more closely these systems, we find a conception of philosophy not really so very different from that which had obtained before.  We do not find, it is true, that disinterested passion for the attainment of truth which is the glory of science.  Man seems quite too much concerned with the problem of his own happiness or unhappiness; he has grown morbid.  Nevertheless, the practical maxims which obtain in each of these systems are based upon a certain view of the system of things as a whole.

The Stoic tells us of what the world consists; what was the beginning and what will be the end of things; what is the relation of the system of things to God.  He develops a physics and a logic as well as a system of ethics.  The Epicurean informs us that the world originated in a rain of atoms through space; he examines into the foundations of human knowledge; and he proceeds to make himself comfortable in a world from which he has removed those disturbing elements, the gods.  The Skeptic decides that there is no such thing as truth, before he enunciates the dogma that it is not worth while to worry about anything.  The philosophy of each school includes a view of the system of things as a whole.  The philosopher still regarded the universe of knowledge as his province.