'What is essential is invisible to the eye,' a fox tells the little prince. 'It's only visible to the heart.' The line is from Antoine de Saint-Exupery's beloved 1943 novella, 'The Little Prince.' It's also on a t-shirt that's selling in the lobby of the Broadway Theater during the four-month run in New York of this touring stage version by a French creative team, all of whom are making their Broadway debuts. The line is unintentionally ironic when the narrator utters it on stage, though, because this 'The Little Prince,' - half dance-theater, half circus acrobatics - is a half-hearted theatrical adaptation that's almost entirely visual. There are very few words, and they are upstaged by the vivid video projections that serve as backdrops. The only character who speaks is the narrator, mostly in English but sometimes in French*, portrayed by Chris Mouron, who also wrote the libretto (such as it is) and co-directed the production.