Voltaire's pairing of reading and dancing is quietly subversive—he's defending pleasure itself as morally sound, which challenged the grim asceticism of his era. Notice he doesn't claim these activities improve us or build character; their value lies simply in being harmless joys, a radical notion when many authorities viewed leisure as a gateway to sin. A teenager scrolling through books and dancing to music in her room is living out his argument: she's choosing two forms of freedom that threaten no one and enrich her own existence. The quote's genius is its modesty—by insisting these pastimes won't harm the world, Voltaire sidesteps the need to justify them as useful, and that refusal to apologize for happiness remains quietly defiant.