Lyric discussion by ScubaSteve84 

Cover art for The Light lyrics by Spock's Beard

This is one of my favorite songs as well, and im_a_pirate's explanation makes a lot of sense. When I first heard the song though, I took something completely different from it, so I thought I'd share that:

Suppose "the light" is the light of happiness, and the song is about one man trying to figure out who he is and who he needs to be. He's going through phases where he's trying to be an average joe (critical masses), a person of influence (centerfold), a stoner (garden people), a loner (man in the mountain), a daily party-goer who lives in the moment (senor velasco) and a punk who doesn't care what people think (catfish man). Then finally he asks, which is the path in life that will lead me to true happiness? ("where is that straight line that I can hold up to the light?")

It's more of a reach I guess, and probably influenced by my own experiences, but then that's kind of the point. Anyway, I'm not saying it's the right or best explanation, just an alternate one to think about.