Si Morley chooses to live in the New York of 1882. He finds that old New York has a quality of life that modern New York cannot match. Although more primitive in technology, its citizens have a joyousness about life, a knowledge of why they are alive, that twentieth-century New Yorkers no longer possess. Two world wars and a current desultory military action in Vietnam, Si Morley discovers, have taken the spirit out of people and have left them confused about the purpose of living.

Nor is the problem just the people. The physical structure of New York City shows the differences. The New York City of 1882 is a rainbow of rural, suburban, and urban landscapes. Walking a few blocks in any direction will take Morley from commercial center to quiet residential neighborhood to active farmland, without ever leaving Manhattan island. Contemporary New York City, however, is all concrete and steel, unvarying canyons of high-rise apartment and office buildings.

The third theme of the novel is Finney's contribution to the ongoing debate among fantasy writers about time-travel. If someone from the present travels into the past, will their actions change the past and therefore the future known today as present? Si's visit to the past is made possible by a secret government experimental unit. Once time travel is proved possible, the project directors begin speculating upon the possibility of changing the past deliberately. Si chooses at this point to enter the past permanently, unwilling to see how government bureaucrats think the present should be improved.