I don't know what it "means", but it's one of my favorite albums and concepts. It's centered around the Fibonacci sequence, and incorporates it all over the place in time signatures, the patterns of syllables in the lyrics, lyrical themes, and the artwork. I liked the album before knowing the extent of it, and think my head exploded when I heard about some of the neater uses. Tool may be a pretentious band, but damn it if that album isn't both beautiful and brilliant.