In Pablo Neruda's early poetry, he used stanzas, rhyme and syntax, however, as he got older, for instance publishing a book in 1933, his poetic technique changed drastically.
In [Residence on Earth], Pablo Neruda moves beyond the lucid, conventional lyricism of Twenty Love Poems, abandoning normal syntax, rhyme, and stanzaic organization to create a highly personalized poetic technique.
It is impossible to say what the author of poetry or the painter of a portrait means, unless he or she explains the piece. Different people will perceive different meanings to all kinds of art: in this case, Neruda's poem, "Lost in the Forest."
First of all, I do not think that "mind/behind" is a purposeful rhyme. There is no other rhyme used in the poem. I can only guess that the words are close because of what Neruda was trying to say in his poem. It has also been noted (I would assume by those who spoke his native tongue) that some of Neruda's musical quality is lost when his poems are translated from the Spanish to the English. I can only assume this to be true.
Generally, a poem is written to be musical. The poetic devices an author uses are especially important to the sound of the poem, and this is also why poetry is best read aloud. Poetic devices that lend themselves to the musical quality of a poem include assonance, consonance, alliteration, and onomatopoeia. The ear picks up these things much more quickly than the eye.
We find assonance in the following line that uses the "soft" "I" sound, as found in "whisper." Note the sound of the words: "twig," "lifted," "its," "whisper," and "lips." The repetition of these sounds support the sense of a "whisper."
and lifted its whisper to my thirsty lips...
However, traditional poetic devices, in terms of assonance, don't seem to be used purposefully to achieve a specific response from the reader.
Another thing that is present that is generally considered a poetic device is onomatopoeia. Words that fall into this category are: "whisper," "cracked," and "muffled." Poetic devices are supposed to provide a poem with a musical sound; perhaps the reason that I do not find a musical quality is that it has been translated from the Spanish, or that the topic is not one that makes Neruda feel musical. The tone of the poem (and the mood) seem to speak to the loss of something in childhood. Words that set the mood for me are: "lost (used twice)," "broke," "thirsty," "cracked," "torn," "muffled," "darkness," "cried," and "wounded."
With these words in mind, I feel that Neruda is attempting to share with the reader the sadness over something lost of his childhood, and for me the words listed actually achieve this, where assonance, consonance, alliteration and onomatopoeia traditionally do in other poetry, but not here.
Traditional poetic devices are seen in the work of Poe and Coleridge, but Robert Frost commented on the use of sounds in poetry:
'One of the things that I notice with myself is that I can't make certain word sounds go together, sometimes they won't "say." This has got something to do with the way one vowel runs into another, the way one syllable runs into another. And then I never know — I don't like to reason about that too much. I don't understand it, but I've changed lines because there was something about them that my ear refused. And I suppose it has something to do with vowels and consonants.... I don't want any science of it.'
Perhaps Neruda's words don't "say" to us here.