I never knew whether to pity or congratulate a man on coming to his senses.

Thackeray’s line plays on the ambiguity of “coming to one’s senses” as both a recovery (from illusion, passion, or folly) and a loss (of hope, romance, or comforting self-deception). To “congratulate” someone suggests that clear-sightedness is a gain—maturity, sobriety, and better judgment. To “pity” him implies that the same clarity can be painful: reality may be harsher than the dream it replaces, and self-knowledge can arrive with regret. The epigram captures a recurrent Thackerayan theme: the cost of disillusionment in a world where vanity and social pretenses often sustain people as much as they mislead them.