This song is classic Hermeto Pascoal. It contains some of the quitessential elements of his style. The most obvious “Pascoalism” is the melody itself; full of long runs of 8th notes, often featuring doubled tones both on and off the beat. The bassline is a counterpoint to the melody, not always related to the harmony, as in bar 9 where the bass plays E and A naturals over the Eb and Ab chords. The harmony seems to dance around a Bb lydian tonality before settling on C minor for the remainder of the tune.
Hermeto builds momentum at the D.S. by moving from a downbeat-heavy melody to a more syncopated rhythm. He makes life easy for the soloist by vamping on one minor chord instead of complicated changes, a techinque also favored by Frank Zappa. Another hallmark of Hermeto’s writing is metric modulation. The tune speeds up twice during the first head (ignore the modulations after the repeat). Note the 1st ending repeats all the way back to the bar of 2/4 at the beginning.