It is true that pleasure is the summum bonum of Epicurus, but his conception of that pleasure is profoundly modified by the Socratic doctrine of prudence and the eudaemonism of Aristotle.
Yet the idealistic postulate of a summum bonum is in result optimistic, and this view predominated among the Stoics and the Neoplatonists.
Though duty, in his view, excludes regard for private happiness, the summum bonum is not duty alone, but happiness combined with moral worth; the demand for happiness as the reward of duty is so essentially reasonable that we must postulate a universal connexion between the two as the order of the universe; indeed, the practical necessity of this postulate is the only adequate rational ground that we have for believing in the existence of God.
He seems to have been much indulged, and to have led a very pleasant life of it; he pleased himself in moderate excursions, frequented the theatre, mingled, though not very often, in society; was sometimes a little extravagant, and sometimes a little dissipated, but never lost the benefits of his Lausanne exile; and easily settled into a sober, discreet, calculating Epicurean philosopher, who sought the summum bonum of man in temperate, regulated and elevated pleasure.
Thus the summum bonum for man is objectively God, subjectively the happiness to be derived from loving vision of his perfections; although there is a lower kind of happiness to be realized here 1 Abelard afterwards retracted this view, at least in its extreme form; and in fact does not seem to have been fully conscious of the difference between (I) unfulfilled intention to do an act objectively right, and (2) intention to do what is merely believed by the agent to be right.
If, however, we abandon intuitional ethics, it is reasonable to argue that the term summum bonum ceases to have any real significance inasmuch as actions are not intrinsically good or bad, while the complete sceptic strives after no systematic ideal.