Pablo Neruda's "If You Forget Me" is the quintessential love poem. It is beautiful. The author's use of imagery is a powerful tool in driving home his dedication to the woman he loves. There are many uses of imagery in the poem: I will highlight three.
Imagery is anything that brings an image into the mind of the reader; in fact, imagery is found in the use of similes, metaphors, hyperbole, personification, or detailed descriptions, especially those using sensory details. Neruda's poem has lovely imagery. The first describes nature, the world seen outside the author's window at night, especially with the "crystal moon," "red branch" and "slow autumn:"
...if I look
at the crystal moon, at the red branch
of the slow autumn at my window...
Another example of imagery is found at the fireplace, in the impalpable ash (so fine a powder, that it contains no "grit") of old fires, and the promise of another—in the "wrinkled" log. Sensory details appealing to touch and vision make the imagery that much more impactful; the description of "near the fire" may bring to mind associations he holds with the literal fire and the fire of their passion.
...if I touch
near the fire
the impalpable ash
or the wrinkled body of the log...
One more example of imagery is found in the metaphor found at the end of the first full stanza. The speaker comments on a list of sensory elements, appealing to the sense of smell (aromas), of sight (light) and of touch (metals). These elements, or senses, he describes as small boats that journey between he and his lover.
...everything carries me to you,
as if everything that exists,
aromas, light, metals,
were little boats
toward those isles of yours that wait for me.
Throughout the poem the speaker notes that he will mirror whatever behavior is exhibited by his lover. If she forgets him or leaves him, he will immediately do the same...so he says. However, the vivid images of devotion (even if lost), up until the strength of the last stanza, leaves me with the feeling that the speaker is deeply in love, and regardless of his words, his love will not disappear as easily as he might light to let the reader believe.