The primary theme of the passage is the isolation and defeat of individuals in society.
This is evident as the character Gortsby reflects on his own feelings of disillusionment and observes the people around him, seeing them as individuals who are struggling and defeated. The descriptions of both the elderly gentleman and the young man emphasize their unhappiness and sense of loss, highlighting the loneliness that many experience despite being in public spaces. The overall mood suggests a contemplation of defeat rather than celebration or community.