Expositio super symbolum Nicenum

And in one Lord.

Just as the first article turns upon the Father, so the second turns upon the Son. Many articles, however, turn upon those things which pertain to the Son — for example, the seven seals with which is sealed the book which John saw in the Apocalypse, which no one was able to open except the lion of the tribe of Judah.¹ These are, namely: conception, birth, passion, descent into hell, resurrection, ascension, the second coming to judgment.

The second article embraces four things. For it implies that the Son is true God, that he is other in person from the Father, coeternal with the Father, consubstantial. It says therefore: and in one Lord.

Christ, according as he is God, is called Lord by the authority of lordship. Yet according to his human nature he is called Lord according to that nature by which he accomplished the sacraments of our redemption, and especially after the resurrection, in which both his natures were glorified. Hence in the Gospel Christ is called Lord after the resurrection, not before.

Hence too those in the cloister, in the reading of the Gospel, when they speak of him, call him Lord. This, however, is especially to be done in those Gospels which contain the things which the Lord Jesus did after the resurrection. It says therefore: and in one Lord.

This is said against Nestorius, who did not assert that Christ was true God, but only by adoption. Hence he used to say: "What great thing is it for Christ to be God? I too can be a god if I wish." But Christ alone was Lord, by the accomplishment of the sacraments and the redemption of the human race.