Be thou erect, or be made erect. Just as it is with the members in those bodies which are united in one, so it is with rational beings which exist separate, for they have been constituted for one co-operation. And the perception of this will be more apparent to thee, if thou often sayest to thyself that I am a member (melos) of the system of rational beings. But if (using the letter r) thou sayest that thou art a part (meros) thou dost not yet love men from thy heart; beneficence does not yet delight thee for its own sake; thou still doest it barely as a thing of propriety, and not yet as doing good to thyself.
Do not look around thee to discover other men's ruling principles, but look straight to this, to what nature leads thee, both the universal nature through the things which happen to thee, and thy own nature through the acts which must be done by thee. But every being ought to do that which is according to its constitution; and all other things have been constituted for the sake of rational beings, just as among irrational things the inferior for the sake of the superior, but the rational for the sake of one another.