"One Last Thing"

“Why do you bring that up again?”
“There’s one last thing I want to know—“
“But, dear Sal, you’re listening, you’re sitting there, we’ll ask Sal. What would he say?”
And I said, “That last thing is what you can’t get, Carlo. Nobody can get to that last thing. We keep on living in hopes of catching it once for all.” (page 48)
The "last thing" in the above quote is the thing which will satisfy one’s being, feeling as though one has completely finished something and has no need to search anymore. I find this passage interesting because it seems to me, although somewhat critiquing this quixotic notion of living in search for something no one can ever achieve, that this in fact is something that spurred Sal himself towards taking to the road. He left his home because all of his curiosity for the place had evaporated. His home had become somewhat dead to him. He went in search of something new, something fresh, something alive, something he didn’t know. Denver in itself becomes a wild road trip for Sal as he zooms around with all his friends, getting seemingly very little sleep. It is as if Sal is afraid to sleep too much because he might miss that next thing that he is in search of. And it seems like wherever Sal goes, this is the way he must live. Never really resting, always on the go. It is as if this is the only way he feels that he can get at what he is trying to find. But this next thing isn’t the last thing he will be searching for in life. The search and discovery of this next thing, whatever it may be, which could even be the road trip itself, is just another phase in his life. And after this next thing he will be in search of another thing and another thing after that and so on. There is never a last thing and can never be a last thing. And with this attitude, he fails to look in the crevices of life, to dig deeper into the things around him to get to know what they are really all about. He seems to only absorb the very surface of things. He meets people that seem to move him and he fails to get to know them. He fails to carry with him from his encounters with others their true identities, only his image of their true identities.
In my opinion, if he slowed down a little he could get a lot more out of where he is and have time to reflect on where he has been. Maybe if he slowed down, his relationships with the people he meets on the road would be more meaningful and he could find what he is looking for faster and have it last longer.
Is there anything that is ever really complete? The more empty a person’s life is, the more that person frantically searches for something to fill their lives. Could this be the case for Sal?