Marcel Duchamp labored in secret for 20 years to produce what the painter Jasper Johns has called "the strangest work of art any museum has ever had in it." He might be right: The diorama known by its abbreviated French title Etant donnes is spectacularly bizarre, enigmatic, mysterious, disturbing, captivating, and, perhaps to some observers, repellent.
None of those attributes is obvious, because Etant donnes is also as secluded as a cloistered nun. It has been one of the Philadelphia Museum of Art's cherished masterpieces for 40 years, yet I'll wager that - Duchamp partisans excepted - most visitors have not seen it or even been aware that it exists.
Étant donnés doesn't attract crowds because it can be viewed by only one person at a time. Furthermore, Duchamp restricted what the solitary viewer could see: He or she must stand in one spot and peer through two peepholes in an antique wooden door, like watching a baseball game through a knothole in the outfield fence.
"Étant donnés" continues in Galleries 181, 182 and 183 of the modern-contemporary wing at the Philadelphia Museum of Art, 26th Street and the Parkway, through Nov. 29. Hours are 10 a.m. to 5 p.m. Tuesdays through Sundays and to 8:45 p.m. Fridays. Admission is $16 general, $14 for visitors 65 and older, and $12 for students with ID and visitors 13 to 18. Pay what you wish first Sunday of the month. Information: 215-763-8100, 215-684-7500 or www.philamuseum.org