(Perhaps about a.d.357 or 358; in answer to a letter which is not now extant.)

I have failed, I confess, to keep my promise. I had engaged even at Athens, at the time of our friendship and intimate connection there (for I can find no better word for it), to join you in a life of philosophy. But I failed to keep my promise, not of my own will, but because one law prevailed against another; I mean the law which bids us honour our parents overpowered the law of our friendship and intercourse. Yet I will not fail you altogether, if you will accept this offer. I shall be with you half the time, and half of it you will be with me, that we may have the whole in common, and that our friendship may be on equal terms; and so it will be arranged in such a way that my parents will not be grieved, and yet I shall gain you.