The title is from a U2 song: I think it's a great metaphor for our life's journeys and experiences.
The Edge answered the question about the lyrics in an interview:
"I think lyrically it's very personal to Bono. The idea for the song lyrically, the one step closer to knowing line, came out of a conversation he was having with Noel Gallagher (of Oasis) about his father's illness, which at that point he'd found out was terminal. They were talking about how weird it was to know that your father's dying, and Bono was saying, I'm not sure he has a faith, whether he knows where he's going, and Noel says "Well, he's one step closer to knowing, isn't he!” and Bono went "Yeah”. (http://www.u2achtung.com/00/htdaab/interview.php)