One thing that Jeff dances around and sometimes mentions is that his "renaiissance" came with his finding the love of his life. It happened later for him than for many, and I don't believe that every couple experiences true love. But once that happens, everything changes. With children, even more so. Once someone finds something more valuable than money, more valuable than security, more value than safety, then that someone may consider more universal truths. Like whether what we see is "real", whether any of it is important and what our purpose truly is. Jeff always evades the possibility of the existence of God, but his thought process is clearly pointing him toward that realization, whether he admits it or not.