Good (Lat. bonum) is variously defined by moralists, according to the nature of their ethical theories. The Stoic would define it to be that which is according to nature; the Epicurean, that which increases pleasure or diminishes pain; the Idealist, that which accords with the fitness of things; the Christian theologian, that which accords with the revealed will of God. So the philosophical schools give various and even contradictory definitions of the highest good (summumsbonum). Thus Aristippus placed it in pleasure in activity; Epicurus, in pleasure in repose; Zeno, in tranquillity of mind; Kant, in well being conditioned on morality; the Materialists, in self-love.
Schleiermacher states his views of. the subject as follows: In ethics there are three fundamental conceptions — duty, virtue, good. Duty is the obligation of morals action; virtue is the moral power of the agent; the highest good is the objectives aim of both. In the Systems of Kant and Fichte, ethics is the doctrine of duty, and its development becomes simply a treatment of individual virtues. In opposing this view, Schleiermacher maintains that a system of moral precepts, or formulas of duty, even though it might embrace the whole life of man, could only be applied in isolated cases and single acts, leaving the moral life as a whole. still unexplained. It is only in a very limited sphere that a moral agent acts alone, and without reference to other agents; and his virtue has relation to a general state of things, to produce which other agents cooperate. Schleiermacher charges the existing ethical systems with making an unnatural schism between the law of action (duty) and the active power (virtue) on the one hand, and the resulting actions on the other hand; and also with leaving entire spheres of human action, of unquestionably moral character, in the domain of adiaphora (things indifferent), instead of brinmging them under the authority of moral law. To remedy these alleged confusions, Schleiermacher seeks for an organic principle of ethics, which shall be at once objective, systematic, and comprehensive. He finds it in the highest good, which can be completely apprehended, not in its relations to the individual merely, but with reference to the human race as a whole. From this principle the whole sphere of ethics may be mapped, placing universal nature on the one hand, and the organizing reason (the universal reason of humanity) on the other. In this theory Schleiermacher expressly recognizes the authority of Plato, who, in his Philebus investigated the "highest good." Aristotle, in whom the idea of virtue was the highest, places the highest good in εὐδαιμονία, individual happiness — not, however, in the Epicurean sense, but in the sense of ζωῆς τελείας ἐνέργεια κατ᾿ ἀπετὴν τελείαν, the working out or realization of a perfect life through perfect virtue.
In the further development of the history of ethics, so far as relates to the definition of the "highest good," we must particularly notice the distinction (1) between the individual and the general, indicated in Plato and Aristotle, and carried to the greatest extent by Epicurus and the Stoics; (2) the resulting distinction between the objective and subjective, according to which the "highest good" is, on the one hand, a condition of man (e.g. Epicurean enjoyment, Stoical endurance); or, on the other hand, a product of human activity, the end of humanity as a whole;. (3) the consequent moral theories of pleasure or of activity, according to the farmer of which the "highest good" lies in enjoyment, while according to the latter it lies in moral activity. In the language of Christian theology "the highest good" is the kingdom of God, which includes within itself all ethical elements, the individual and the general, activity and happiness, theory and practice, means and end. The means of securing the "highest good" is to promote the advancement of that kingdom; the end, the "highest good" itself, is the coming. of that kingdom, to the individual. in his personal salvation to the universal race, in the realization of the promise "God shall be all in all!" See Schleiermacher, Ethische Abhandlungen, in his Phil. Nachlassen, 2:12, 13; Herzog, Real-Encyklop. s.v. Ethik, Tugend.