Plato seizes the weapons of his great master, and is imbued with his spirit. He is full of hope for science and humanity. With soaring boldness he directs his inquiries to futurity, dissatisfied with the present, and cherishing a fond hope of a better existence. He speculates on God and the soul. He is not much interested in physical phenomena; he does not, like Thales, strive to find out the beginning of all things, but the highest good, by which his immortal soul may be refreshed and prepared for the future life, in which he firmly believes. The sensible is an impenetrable empire; but ideas are certitudes, and upon these he dwells with rapt and mystical enthusiasm,--a great poetical rhapsodist, severe dialectician as he is, believing in truth and beauty and goodness.
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.
Cicero was the first to systematize the philosophy which contributed so greatly to his intellectual culture, But even he added nothing; he was only a commentator and expositor. Nor did he seek to found a system or a school, but merely to influence and instruct men of his own rank. Those subjects which had the greatest attraction for the Grecian schools Cicero regarded as beyond the power of human cognition, and therefore looked upon the practical as the proper domain of human inquiry. Yet he held logic in great esteem, as furnishing rules for methodical investigation. He adopted the doctrine of Socrates as to the pursuit of moral good, and regarded the duties which grow out of the relations of human society as preferable to those of pursuing scientific researches. He had a great contempt for knowledge which could lead neither to the clear apprehension of certitude nor to practical applications. He thought it impossible to arrive at a knowledge of God, or the nature of the soul, or the origin of the world; and thus he was led to look upon the sensible and the present as of more importance than inconclusive inductions, or deductions from a truth not satisfactorily established.
Cicero was an eclectic, seizing on what was true and clear in the ancient systems, and disregarding what was simply a matter of speculation. This is especially seen in his treatise "De Finibus Bonorum et Malorum," in which the opinions of all the Grecian schools concerning the supreme good are expounded and compared. Nor does he hesitate to declare that the highest happiness consists in the knowledge of Nature and science, which is the true source of pleasure both to gods and men. Yet these are but hopes, in which it does not become us to indulge. It is the actual, the real, the practical, which pre-eminently claims attention,--in other words, the knowledge which will furnish man with a guide and rule of life. Even in the consideration of moral questions Cicero is pursued by the conflict of opinions, although in this department he is most at home. The points he is most anxious to establish are the doctrines of God and the soul. These are most fully treated in his essay "De Natura Deorum," in which he submits the doctrines of the Epicureans and the Stoics to the objections of the Academy. He admits that man is unable to form true conceptions of God, but acknowledges the necessity of assuming one supreme God as the creator and ruler of all things, moving all things, remote from all mortal mixture, and endued with eternal motion in himself. He seems to believe in a divine providence ordering good to man, in the soul's immortality, in free-will, in the dignity of human nature, in the dominion of reason, in the restraint of the passions as necessary to virtue, in a life of public utility, in an immutable morality, in the imitation of the divine.