In this poem, the speaker expresses all of the myriad ways that she loves her beloved, to whom she speaks (this is a device called apostrophe: when the speaker addresses someone who is absent or dead or cannot respond). She says that she loves him as far as her "soul can reach" and during the day and at night, by "candle-light." She loves him "freely," as though it were a moral requirement, and "purely," because she must. She loves him "with the passion put to use / In [her] old griefs, and with [her] childhood's faith," with the force of the strongest feelings known to both old and young. She loves him with a force she didn't think was still possible, with a love she last experienced when she was young and had heroes and "saints." She loves him with all of her, her happiness and sadness, her body and soul: everything that is her. Finally, she says that, if God allows it, she will continue to love him, and to love him even "better," after her death. Ultimately, then, the poem's theme is that true love knows no bounds, not even the grave.