Memory usually gets good press: it is supposed to keep the past safe for us. Mary Elizabeth Coleridge's twelve lines turn that idea inside out. Here memory is an intruder the speaker cannot evict and, more unsettling, cannot truly bring herself or himself to want evicted. The poem's central idea is that the pain of remembering and the sweetness of remembering are the same thing, so there is no way to keep one and refuse the other.
The first stanza opens with a bewildered address: "Strange Power, I know not what thou art, / Murderer or mistress of my heart." The speaker cannot decide what memory is, and the poem never decides for them. The two nouns sit close together, joined by the shared *m* of "Murderer" and "mistress" (and, quietly, of the title), as if they were two faces of one figure. "Mistress" is a clever choice, because it means both a lover and a woman who rules. Memory is therefore something desired and something in command. The speaker then makes a startling comparison. They would rather take "the blow / Of my most unrelenting foe" than live as they do now, "Slain twenty times a day." The logic is exact. An enemy strikes once and is done, while memory kills over and over without ever finishing the job. The dashes around "as now I live" make the line stumble, as though the speaker must pause to admit how bad things are before reaching the verdict, "by thee."
The second stanza turns on "Yet." The speaker tries to "command thee hence," a phrase with the ring of an order to a servant, but memory "mockest at the vain pretence." The power relationship is plain: the speaker only pretends to be in charge. What follows is gentler and stranger. Memory comes "Murmuring in mine ear a song / Once loved, alas! forgotten long." The word "murmuring" is soft where "slain" was brutal, yet it is the same visitor. There is a paradox in the song as well. It was "forgotten long," so memory is not only keeping hold of the past but dragging up things the speaker thought were gone for good. Then comes the kiss "on my brow," a tender, almost blessing-like gesture, and the speaker admits it is something "I would rather die than miss." The poem never says what or whom is remembered, and that silence lets the situation fit nearly any loss.
The form is small and tightly controlled. Both stanzas are six lines of rhymed couplets in iambic tetrameter, a bouncy, almost nursery-rhyme measure. That neatness works against the content. The rhymes click shut with a calm confidence ("blow" and "foe," "hence" and "pretence") while the speaker's feelings are in turmoil. The strongest design choice is the echo between the stanzas. In the first, the speaker "would rather" face a killing blow than endure memory. In the last line, they "would rather die" than lose memory's kiss. The same construction, with death as the measuring stick, is turned to opposite use, and this reversal shows how thoroughly divided the speaker is. The closing rhyme of "kiss" with "miss" is also telling, because "miss" can mean to lack and to long for. The pleasure and the ache are fastened together in the very sound of the line. The archaic "thou" forms and "mockest" give the address a formal, almost prayer-like tone, as if the speaker were petitioning a god or a tyrant and not simply thinking about the past.
The poem matters because it refuses the comfortable lines we are used to about memory, that it heals or that it consoles. It admits that to remember is to be wounded and to be loved in the same moment, and that a person might choose the wound rather than lose the love. Few poems say so much about grief in twelve short lines, and fewer still leave the central question, "murderer or mistress?", honestly unanswered.