BoC have expressed on numerous occasions their interest in the links between music and mathematics. This particular track is a musical palindrome.
Samples / Lyrics
The theme "The Past Inside The Present" is continued within this track. In addition to these vocals, there is a soft "Purple" uttered twice during this song, first at the 3:52 mark and then again at 3:54.
[dave_from_2001] suggests that the voice near the end (around 3:52) could be saying "be careful".
The vocoder that enters at 1:15 is believed to be saying "We all fall down". (Or possibly "yel-low ball.")
Ranked #384 on Pitchfork Medias top 500 Songs of the 2000's.