Reminiscent of Jean-Luc Godard’s celebration of the mystery and vulnerability of his muse Anna Karina in Bande à part, Noah Baumbach’s love poem to Greta Gerwig is an effervescent, seeming effortless comedy about a young woman taking the first shaky, post-Ivy League steps in what will become her real life. Similarly, Gerwig, who also co-wrote the witty, articulate script, leaves her Mumblecore identity far behind. Her Frances arrives in New York determined to become a post-modern dancer despite the fact that she’s constantly falling over her feet or putting one of them in her mouth. The movie is lightning-in-a-bottle–deft, sophisticated, and, in its myriad shades of digital gray, radiantly beautiful in a brand new way.