Lyric discussion by vibgyor 

Cover art for Music Is Math lyrics by Boards of Canada

Math is describing states, states have their past inherent (like the billion years long past of a stone formed his present appearance) therefore math also describes their past, or could. Considering that BoC is putting very special emotions into their tracks, and Geogaddi alone is an overwhelming experience of an emotional journey (for some, at least for me) btw, the 'past inside the present' could be a description of the music... or everything.

The thing at the end sounds like purple to me, too. uhm, but purple...i heard somewhere it stands for spirituality. maybe it is 'be careful', that would make more sense.