In Brahms' "Die Mainacht," the poetry plays a large part in how the song is structured. The character in this poem is the typical overly-depressed musician, who is really a hopeless romantic at heart. The character goes through three different stages in this song (please keep in mind that poetry is subjective and can have multiple meanings or interpretations) : 1. The character wanders about in nature and "sets the scene" to unload his depression on any willing listener. 2. The character witnesses beauty and love around him but only feels more bitterness about being alone. 3. The character has a major pity-party about not being able to find his soul-mate here on earth. Let's look at each of these sections individually.
One way Brahms sets his music to fit the poetry is (as mentioned in the book) by inverting almost every chord. Also, the Brahms creates ridiculously long phrases in this song to portray the unending search of the character. For instance, let's look at the chords of just the first 8 measures: I64, V, I64, V7, iii, I64, I6, vi, iihd65, IV7, iv, and finally a V. Personally, I don't even really consider this a half cadence because the V continues into measure 9 and starts a new phrase with the poetry, making it sound even more unfinished than the traditional half cadence and also straddling the singer with the responsibility of carrying on the true phrase which does not end until measure 14. (Luckily the singer gets to bow out halfway through m.13). If I had the voice to sing this piece, I would try to make this first section keep moving without any resolve until the middle of 13.
The second section Brahms creates a very obvious switch of mood to fit the poetry by modulating to D major at m.15. This is pretty sudden considering the listeners have just been hit with a minor i chord to end the first section. This section is perhaps the most romantic part of the song. The poet is speaking of the beauty of nature and a pair of doves. Brahms' really plays up this romance by using chords with a prettier harmonic color, setting the voice a little bit higher, and putting the staccato eight notes in the bottom of the piano part with legato right hand soaring above it. To me, this represents the character's beating heart and genuine wish for true love. Speaking of the cooing of the doves, Brahms uses a V/V42 going to a V6; the character has happy, yet unfinished thoughts about love. His true ambivalent feelings come out in measure 21 when the character says "but I turn away, seeing darker shadows." Brahms dabbles in b minor starting in m.21 and uses darker harmonic colors to fit the "darker shadows" such as the viid7 chord in m.22 or the vi6 going to i in m.24. Brahms ends this section with a half cadence in m. 26 under the word "shadows." This gives the listener an intense idea of the real emotions the character is going through just by looking at the doves and feeling alone. If I were singing this piece, I would, once again, treat this individual section as one long phrase and try to keep the momentum going until m.26. I would also color my tone differently depending on the poetry, for instance : "pair of doves" should be a lighter color than "shadows."
I know this must be a strange interpretation to categorize m.27-33 in section 3, but I really think that it acts as a transition to section 3 and that the half cadence and fermata in m. 32 is used as a dramatic effect to make the character's feelings of loneliness, impatience, and searching more exposed to the listener. Measure 33 begins similarly to the first section of the piece with a I64 chord and a similar melodic line, but this section has more root position chords- perhaps to confirm what the poet mentioned earlier in the poem about his loneliness. Maybe at this point the poet isn't searching quite as much and is just stating his need for stability instead of displaying his instability. Measures 33-38 look like this: I64, V7, iii, I64, I6, vi, iid, i, IV6, IV, iid, V. Although this cadence sounds a little more complete than the previous half cadences, this phrase still continues through until the end. Brahms implies this long phrases by his use of the half cadence, the moving piano part, and the unfinished thought in the poetry. The next line starts with "and" then the character re-states what he already said about the flowing tear, only this time it's more descriptive and final. The singer must be more sustained and have a larger sound because of the thicker texture Brahms placed in the piano. Where does the phrase really end? Although the singer ends in measure 48 with a I chord and the poetry is over, the great thing about music is that the music becomes part of the poetry. The character isn't actually done speaking until the piano expresses final thoughts in measures 49-51. I think this is why Brahms placed a fermata over the rest and the final I chord. The singer must hold on to his audience through his nonverbal communication all the way until the end of the fermata, and the pianist must finish the piece by giving the listener a contrary statement. What do I mean by contrary statement? Well, the singer's final line is descending to represent the character's tear and the piano part has an ascending line with mostly happy chords (only one fully diminished ii chord in the last measure) to give contrast and show that the character really is alone.
Before I end, I really must recommend that everyone who reads this (who am I kidding?) go listen to Fischer-Dieskau sing this song. In my opinion, his interpretation is top-notch and his never-ending phrases are to-die-for. And his "Schatten" is perfect! He does a great job at text painting.