We must consider both the ultimate end and all clear sensory evidence, to which we refer our opinions; for otherwise everything will be full of uncer… - Epicurus

A true friend will partake of the wants and sorrows of his friend, as if they were his own; if he be in want, he will relieve him; if he be in prison, he will visit him; if he be sick, he will come to him; nay-situations may occur, in which he would not scruple to die for him. It cannot then be doubted, that friendship is one of the most useful means of procuring a secure, tranquil, and happy life.

Οὐκ ἔστιν ἡδέως ζῆν ἄνευ τοῦ φρονίμως καὶ καλῶς καὶ δικαίως, οὐδὲ φρονίμως καὶ καλῶς καὶ δικαίως ἄνευ τοῦ ἡδέως. ὅτῳ δὲ τοῦτο μὴ ὑπάρχει ἐξ οὗ ζῆν φρονίμως, καὶ καλῶς καὶ δικαίως ὑπάρχει, οὐκ ἔστι τοῦτον ἡδέως ζῆν.

Gentleness, as opposed to an irascible temper, greatly contributes to the tranquility and happiness of life, by preserving the mind from perturbation, and arming it against the assaults of calumny and malice.