In Pablo Neruda's love poem, "If You Forget Me," the author uses beautiful metaphors to attempt to tell his lover that he will forget her if she forgets him, at the same instant this might happen. (Personally, the depth of his feelings in the poem do not convince me that he could let her go as easily as he claims.)
In the first stanza, the speaker compares all of the everyday, mundane things in life as of essential importance because they all lead him to thoughts of her: her very essence is in everything that surrounds him, as she surround him. The ash from old fires, the wrinkled log waiting for the next fire; everything that exists: aromas, light, metals, etc., are little ships that wend their way unavoidably back to thoughts of her. (The elements of his life are compared to little ships that return to her: this is your metaphor.)
...near the fire
the impalpable ash
or the wrinkled body of the log,
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.
Later in the poem, the speaker compares her heart to a plant when he refers to his roots planted there, stating that if she should leave him, he will pull those roots away and find another place to plant them.
...[if] you decide
to leave me at the shore
of the heart where I have roots,
that on that day,
at that hour,
I shall lift my arms
and my roots will set off
to seek another land...
In the last stanza of this wonderful love poem, the direction of the poem shifts as the speaker describes the kind of love that awaits them if she remains with him. The man notes that if she (his lover) will remain true to him, then he will never leave. The speaker uses the images of fire for this final metaphor, comparing her love with his passion, and how the fire of his love will feed off of the fire of her love:
ah my love, ah my own,
in me all that fire is repeated,
in me nothing is extinguished or forgotten,
my love feeds on your love, beloved