travels across the country making whirligigs in honor of Lea, he starts to learn that this can also apply to positive acts:

Brent suddenly thought back to Miss Gill, the mediator in Chicago, and her saying that the effects of an act traveled far beyond one's knowledge. He knew she'd meant harmful acts, like his. He saw now that the same could be said of good deeds, such as a teacher's years of inspiring. Everything we did—good, bad, and indifferent—sent a wave rolling out of sight. He wondered what his own accounting, generations later, would look like.

Brent is used to lying and does not open up to the strangers he meets. In fact, he often tries to avoid conversation:

He was primed to like it, but found it too similar to a small dinner party with strangers, his overly sociable hostess interviewing him about his trip with great interest and trying to get him to converse with the other guests at breakfast. The simplest questions forced him into lies. He preferred the less demanding social life of the bus and restaurants and motels.

In spite of himself, Brent starts to slowly be open to the people around him. After leaving California, he sends a postcard to Emil. He chooses to stop his work to play with the children in Florida for some time.

The children didn't appear the next day. The following day, four of them returned. He took a break, went swimming with them, and learned from a little boy that the ridged, orange shells were called lion's paws and that the birds diving into the water were terns. He didn't mind apprenticing himself to a third-grader. In gratitude, he let the boy drill holes in a long finger of plywood.

The above quote shows how he is willing to learn from the children, and willing to teach them. After mounting the whirligig, he worries the tribute to Lea will be destroyed by a hurricane. But he realizes that he influenced this boy, who in turn could contribute:

Then he noticed the boy who'd drilled holes through the strip of plywood. He'd put a nail through one of the holes, hammered it into the side of a table, and was now blowing on the wood. This improvised propeller budged, then stopped. He blew again, then pulled out the nail and hammered it through a different hole.
Brent watched the boy at work—and cast off all worry about hurricanes. After the storm, new whirligigs would appear.

Although these people are strangers to Brent, he still has a connection to them. Try as he might to remain anonymous, he is still part of a community. He can even play a role in a community that he is not settled down in. This is seen through the effects the whirligigs have on strangers. Even though Brent is just passing through, he can contribute to that community:

He pulled out the book, felt linked with the writer and Emil and the others he'd met on the trip, and walked back inside the office. He placed it on the book exchange shelf, aware he was nudging an invisible gear forward. He wondered who would read it next.

He learns that people are linked, and one act can ripple and inspire more:

It struck him now that the crash wasn't only something that he'd done to her. When they'd met, he was longing to be swallowed by the blackness. She'd set him in motion, motion that he was now transferring to others.

Brent learns to open up. He realizes that simple acts and strangers can still be connected.