Luther commenting on Galatians 5:14 (“For all the law is fulfilled in one word, even in this; Thou shalt love thy neighbour as thyself.”):
...One should also note most carefully that from the words of this commandment some of the fathers drew the opinion that the love here prescribed begins with oneself, because, as they say, love of oneself is prescribed as the rule according to which you should love your neighbor.
I used to think about these things in an effort to understand them, but the exertion is useless. I shall not decide in advance for anyone but shall make bold to set forth my own opinion. I understand this commandment in the following way: It commends love only of one's neighbor, not love of oneself. In the first place, because love of oneself is in everyone inherently. Secondly, because if Paul had meant this to be the sequence, he would have said: “You shall love yourself, and your neighbor as yourself.” But now he says: “You shall love your neighbor as yourself,” that is, just as you already love yourself, without any commandment. But in I Cor. 13:5 the apostle Paul, too, ascribes this quality to love that it does not look for its own advantage, since it completely renounces love of oneself. Christ commands that one deny oneself and hate one's own life (cf. Mark 8:34 f.). And Phil. 2:4 says clearly: “Let each of you look not only to his own interests but also to the interests of others.” Finally, if a man had the right kind of love of himself, he would no longer be in need of the grace of God, because the same love, if it is the right kind, loves both oneself and one's neighbor; for this commandment demands the same love, not another love. But, as I have said, the commandment presupposes that a man loves himself. And when Christ says in Matt. 7:12: “Whatever you wish that men would do to you,” He is certainly declaring that affection and love of self are already present in them; and, as is obvious, He is not commanding it in this passage either. Therefore, as I have said, according to the opinion I make bold to have, the commandment seems to be speaking of the perverse love because of which everyone, forgetful of his neighbor, looks only to his own interests. This, on the other hand, becomes the right kind of love when one forgets oneself and serves only one's neighbor.
From “Lectures on Galatians” (1535) by Martin Luther (Vol. 27, p. 355, Luther's Works, Concordia Publishing House, St. Louis, 1964).