What memory gives Carton comfort as he wanders the Paris streets, and what does it tell us of why he turned out the way he did?

Carton reflects on how he was orphaned at an early age and has never felt at home anywhere. This perhaps explains how his life has turned out. Carton recalls a prayer that he learned when he was younger, and he stops to help a child across the muddy street. This brings him comfort. He also buys a deadly combination of drugs as a last resort.