The show begins with Robert Smythe presenting a lecture about Leonardo da Vinci with the help of a puppet wearing a Mona Lisa T-shirt. This is not really art history, and not really biography, but more a catalogue of career failures. Smythe delivers his lines as though he were talking to not-very-bright, slightly deaf children. If this lecture has a shape and point, it is hard to tell, partly because Daniel Stein — the other middle-aged guy in black onstage — keeps interrupting with cute remarks. This naughty schoolboy routine goes on throughout the very long hour Measuring Man takes.

The show's focus — if there can be said to be one — seems to be on Leonardo's creativity (the plans for human flight, the unfinishable paintings). Smythe interprets Leonardo's attempt to locate the soul inside the human body by ripping apart a paper puppet and finding, inside, Leonardo's self-portrait. Then, both men, in a leap of breathtaking arrogance, become Leonardo, having already paraded their credentials (Stein's devotion to art that wrecks marriages, Smythe's winning a Guggenheim grant despite puppetry being universally disrespected, blah blah blah). In a frenzy of foiled creativity, they enact their own passion and frustration with the artistic process. But what we get is Measuring Man and not Mona Lisa.

There are moments of arresting visual power, but they are rare and short; one of the best is what begins to be a living image of Vitruvian Man — but before it can be completed, they're off onto something else. There is much shadow puppetry, which, surprisingly, seems badly lit and cheesy. Stein flirts with women in the audience, blowing kisses and waggling his eyebrows, treating The Last Supper as a Borscht Belt joke. Smythe tries for "movement" by twirling around the stage, apparently forgetting his own limitations (that's what Leonardo can do to you, I suppose). All told, this show is embarrassing to watch.

Measuring Man Through Oct. 1, Mum Puppettheatre, 115 Arch St., 215-413-1318 or www.livearts-fringe.org