In John Irving's novel "Until I Find You," the character Jack comes to a profound realization about human connections. He reflects on the unexpected emotions that arise when thinking about people from his past, even those he had minimal interactions with or didn't particularly care for. This feeling of missing individuals he hardly knew highlights the complexity of human relationships and how memories can linger long after the encounter.

The theme illustrates that the impact of individuals in our lives can be deeper than initially perceived. As Jack navigates through his life, he learns that the significance of people can emerge from feelings of nostalgia and the shared experiences, no matter how brief, that leave a lasting impression on our hearts and minds.