Talking about the conditional

Last Thursday, after the class, I came across a sentence with an interesting use of conditional. It belongs to a novel  that I'm currently reading, In the Country of Last Things, by Paul Auster. It's a book worth reading (you can find it in the E.O.I. Library). This is the quotation:

"I had no friends, no one to talk to, no one to share a meal with. If not for the picture of Sam, I don't think I would have made it. Just knowing that he was in the city gave something to hope for."