There are two important themes in Donne's poem "The Good-Morrow." First, the poem suggests that one does not really grow up, or fully mature, until one falls in love. Before the speaker found true love with the person he addresses in the poem, he wonders if they were even "weaned till then," meaning that they might (figuratively) still have been breast-feeding, like infant children, until finding love. He claims that the only real "beauty" he knew before meeting his beloved was "but a dream" of her. Only now, having found one another, do their souls awaken and bid "good-morrow," or good morning, to the world; it is as though they were still asleep until they met and loved.

The second of the poem's themes is that nothing that is "mixed equally," or combined and brought together in such a powerful way, can really die. The speaker argues that his and his beloved's love for one another makes them as "one" and that, as long as their love continues in this way, it (and, so, they, in a way) cannot die. Because they "Love so alike" one another, love neither can nor will "slacken," and so it will exist for eternity. The speaker suggests that each partner has become the world to the other, as his eye reflects only her face, and her eye reflects only his face.