I guess I'll be the first one to take a stab at Variation form. This unique piece of music begins quietly while the tenor sings the statement of the sectional variation for 6 measures. This theme is repeated exactly the same 8 more times. There is no variation in the tenor, besides word changes, for a total of 9 statements. The variation in the piece comes with the Horn and strings.
A measure before the tenor ends the statement, the cello and bass enter with the first variation. 5 measures later, the viola comes in with the first variation, and the cello and bass pick up the second variation. Notice how the statement is 6 measures in length, while the variations are all 5 bars long. This creates a cool off balence effect. This stacking affect of adding instruments continues until Box 16, where all the instruments all alternate playing the 4th variation. The strings build until Box 17, where there is a loud, fanfarish horn player coming in with the first variation. The horn is short lived however, and after acting as an accompaniment to the tenor and horn the strings enter back in with the first variation near the end. As we approach the conclusion of the piece, we end just as we started. The tenor sings the unaltered repitition into nothingness.
Well there it is. Not sure what exactly to say, but I gave it my best shot. Hope people have good comments.