There is a distinct difference between the definition of mood and tone in a piece of literature. Neruda's poetry is mesmerizing in the way he conveys his ardor and love for his lover; the mood, which makes the audience feel a certain way, is much different than the tone, which is how the author feels about his subject: and the mood and tone are not always the same.
In Pablo Neruda's poem, "If You Forget Me," the mood is "if you forget me, I'm already gone and I will already have forgotten you." While reading the poem, between the lines, it is hard to accept that the author who so loves this woman could dismiss her as casually as he would ask us to believe. While the mood seems to express "leave me and I'm gone," the author's love for this woman is so strong, it is nearly impossible to credit his ability to disconnect. The mood, therefore, contradicts the tone. The mood generally provides a show of strength while I believe the TONE gives true insight to the author's lack of power to dismiss his sweetheart in light of his heart's complete devotion to her.
Two examples that support the mood are as follows.
One brief example can be found in the following couplet where the author promises his lover that however she acts towards him, he will return the favor. This is the mood: is the author's attempt to make the audience believe he can leave his lover behind in the blink of an eye.
...if little by little you stop loving me
I shall stop loving you little by little...
In the second, more extensive example, the author reminds his lover (with a simile) that his love is like roots in the land, but that he will remove his heart's roots and go to a new land should she leave him. This is his warning to her, to support an alleged detachment he will adopt if she leaves.
...and 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.
However, it is the last stanza that makes me believe that the mood the author creates of personal independence and control are purely words. The tone, however, is very different than the examples the author provides in the body of the poem.
...if each day,
you feel that you are destined for me...
in me nothing is extinguished or forgotten,
my love feeds on your love, beloved,
and as long as you live it will be in your arms
without leaving mine.
While the author tries to convince the audience that he can walk away having lost nothing, the last stanza provides the reader with insight into the connection between the soul of the author and the soul of his sweetheart. The tone is one of complete devotion, regardless of her behavior, which can only then infer as to how devastated he will be if she does, in fact, leave him.