IV.--With regard to the scheme of Duty. In Plato, we find the first statement of the four Cardinal Virtues.
As to the Substance of the Moral Code, the references above made to the Republic and the Laws will show in what points his views differed from modern Ethics.
Benevolence was not one of the Cardinal Virtues.
His notions even of Reciprocity were rendered hazy and indistinct by his theory of Justice as an end in itself.
The inducements, means, and stimulants to virtue, in addition to penal discipline, are training, persuasion, or hortatory discourse, dialectic cognition of the Ideas, and, above all, that ideal aspiration towards the Just, the Good, around which he gathered all that was fascinating in poetry, and all the associations of religion and divinity. Plato employed his powerful genius in working up a lofty spiritual reward, an ideal intoxication, for inciting men to the self-denying virtues. He was the first and one of the greatest of preachers. His theory of Justice is suited to preaching, and not to a scientific analysis of society.
V.--The relation of Ethics to Politics is intimate, and even inseparable. The Civil Magistrate, as in Hobbes, supplies the Ethical sanction. All virtue is an affair of the state, a political institution. This, however, is qualified by the demand for an ideal state, and an ideal governor, by whom alone anything like perfect virtue can be ascertained.
VI.--The relationship with Theology is also close. That is to say, Plato was not satisfied to construct a science of good and evil, without conjoining the sentiments towards the Gods. His Theology, however, was of his own invention, and adapted to his ethical theory. It was necessary to suppose that the gods were the authors of good, in order to give countenance to virtue.
Plato was the ally of the Stoics, as against the Epicureans, and of such modern theorists as Butler, who make virtue, and not happiness, the highest end of man. With him, discipline was an end in itself, and not a means; and he endeavoured to soften its rigour by his poetical and elevated Idealism.
Although he did not preach the good of mankind, or direct beneficence, he undoubtedly prepared the way for it, by urging self-denial, which has no issue or relevance, except either by realizing greater happiness to Self (mere exalted Prudence, approved of by all sects), or by promoting the welfare of others.