When Clifford is feeling his first thrill of freedom after the sudden death of Judge Pyncheon, he drags Hepzibah to a train so that they can go...anywhere. Up until this moment, Clifford has always shied away from trains as too new-fangled for his old-fashioned sensibility. But now that Judge Pyncheon is dead, Clifford is embracing new things. So he leaps onto this train and starts making a scene.
He falls into conversation with a conservative man on the train. This man has a sharp, piercing gaze, but he still can't see through Clifford. Clifford explains his new theory – somewhat in line with Mr. Holgrave's ideas – that we should all become permanent wanderers. He feels that houses only weigh people down with expectations they can never (or should never) fulfill. Instead of getting stuck in houses, we should all live on trains and keep moving, always moving, towards the future. The man on the train thinks Clifford is nuts and keeps trying to get out of the conversation.
Clifford can only sustain this rush of new ideas until his burst of energy runs out. Then he and Hepzibah have to get off the train and go back home. That's the thing about home: it's much more comfortable than always looking for something new, different, and better.