on nights like this I held her in my arms,
my soul is lost without her.

Although this may be the last pain she causes me,
and this may be the last poem I write for her.

In the morning, we get the sense that he will move on and begin his life anew. His "saddest poem" is the final purge of a wonderful and difficult time in his life.

[eNotes editors can only answer one question per posting. Additional questions should be posted separately.]

The tone of the poem "Saddest Poem," which is how the author feels about his subject, is "bereavement;" he is grieving for the loss of his love. And although he says he does not love her, paradoxically, he admits he still does love her: he is enmeshed in the memories of their love together.

I no longer love her, true, but how much I loved her.

Imagery can be found throughout the poem: Neruda, a master of love poetry, also employs beautiful imagery in speaking of the woman he loves. One example deals with the stars. This imagery suggests that their love was beautiful like the stars, and even though the stars are still beautiful, they are now distant and "cold." ("Shiver"could refer to stars twinkling or their temperature, now so much more distant as is his former love). In these lines I believe there is also an inferredmetaphor, comparing their love to the stars: all around him are memories of their love, but their love is not there any longer.

The night is full of stars,
and the stars, blue, shiver in the distance.

Another form of imagery, a simile, is found in the line where Neruda compares the poem falling to the dew on the grass—in that the poem falls lightly to the soul, just as dew falls on grass.

And the poem falls to the soul as dew to grass.

We see imagery again as Neruda describes his lover...her body and eyes:

Her voice, her light body. Her infinite eyes.

Finally, the last two lines of the poem seem like a metaphor as well. Neruda compares the last pain she causes him to the last poem he writes for her, extending the comparison to the pain she creates and the love he reveals (in poetry). It is interesting to note, however, that Neruda chooses to use the word "may" twice...as if perhaps there is hope, for she may cause him more pain and/or, he may write more poetry about her, indicating once more the depth of his love for her.

Although this may be the last pain she causes me,
and this may be the last poem I write for her.

I think this poem is more about the impermanence of Earthly things than it is about love being irreplaceable. The main theme is that while the concept of love seems infinite, love between people is not permanent. Neruda positions this theme against images like the sky and the stars which are infinite when compared to a love that has ended. The speaker is further conflicted because even if he wants to continue to love this woman, he can’t recreate the feeling.
Love is so short and oblivion so long.

The speaker says that his soul is lost without her because his soul is infinite and love is not. It is the “saddest poem” because the speaker can conceptualize what infinitude is but is unable to perpetuate this love. His actual writing about it is another attempt to make this particular love permanent.

On a practical level, this is just human nature. People grow apart and form new relationships. In this case, love has a kind of permanence but only through change. You might say that this means “love is irreplaceable,” but I’d say it’s more accurate to say “love is unrepeatable.” You can’t repeat love but you can replace it with something new. This calls to mind the phrase “if it ain’t new, it’s through.” To perpetuate love, you have to continue to be creative. There is creative promise and hope in that love is so ephemeral and original that it cannot be repeated. As soon as something is copied, it is no longer original or as genuine. But the poem seems to dwell mostly on the loss rather than love as constant renewal. Whenever you try to recreate feelings or situations from your past, you are bound to fail. There is sadness for this loss.