I believe the first eight measures of the piece is a parallel period. Both phrases start with similar harmonic material. The differences are in the cadences. The first phrase ends on a half cadence and the second ends on a perfect authentic cadence. Also both phrases share this cute little eighth note quarter note sequence doo-da thing. Something else I noticed about these first eight measures...the text for the first phrase end on questions so the harmonic language ends on a half cadence to signify the uh questionability of the text, if that makes sense at all, and the text in the second phrase are two statements so the harmonic language end on a PAC. In measure 64, which comes right after a repetition of the first eight measures of the piece, you expect the harmonic structure to resolve to tonic. What happens instead is the structure goes to a PD figure that leads to D and then it finally resolves to T. The reason for this may be because of the text "let me free". That phrase is repeated several times in the piece so I think a tonic chord would just cut that declaration short.
The first two measures of the first phrase is mainly comprised of the PD function while the last two measures goes to D and T. The main difference between the two parallel phrases are the cadences. The first phrase looks like it ends on tonic but then it goes straight to a vi so the harmonic structure wants to go on, but the end of the second phrase sound like there is a rit. and it ends on a very strong tonic chord. Also, in the second phrase the first few measures do an ascending 2nd thing that heightens the emotional feeling of the text. There's a secondary dominant in the first phrase too, 4th beat of ms.66....just thought I 'd throw that in there.
Most of the accidentals are just chromatic passing tones. In the part with the ascending 2nds (ms.69-71) the bass pitches are 5-6 suspensions. As mentioned before there is a secondary dominant in ms.66 (viidim65/ii), the same secondary dominant is also in ms.75, both resolve down to a ii chord. Performance wise I would pay attention to the secondary dominants because they just add the certain je ne sais quoi. In conclusion, the use of secondary dominants in this piece can be quite startling. (i.e. Britney Spears, see picture below, found the secondary dominants in hensel's piece so surprising she almost dropped Sean Preston OMG!!)