For 40 years, evolution, rebellion and resilience have been Madonna’s hallmarks, but forward momentum is her life force. She’s been pop music’s premier shark, operating in near perpetual motion: Why would she pause to bask or look back, and risk losing oxygen?

So there are understandable touches of both defiance and reluctance to the Celebration Tour, her first road show devoted to hits rather than a new album. The retrospective began its North American leg at Barclays Center in Brooklyn on Wednesday night with all the classic trappings of a Madonna spectacle. But unlike her 11 prior tours of this scale, this one was haunted by ghosts — some invited, and some who crashed the party.

The set list began with a moment of birth — not the start of Madonna’s career, but the arrival of her first child — via “Nothing Really Matters,” a song from her 1998 album, “Ray of Light,” about how parenthood rearranges priorities. The anachronism was a table-setter: If Celebration recounts her life story, its arc was animated by her experiences of losing her mother and becoming one, herself. “Never forget where you came from,” she instructed a dancer who served as an avatar for her younger self, whom she then gave a maternal hug.