The Sleeping Gypsy is one of MoMA's most popular paintings.

Gypsy also marks a tectonic shift in the history of the museum. Less than ten years after the institution's founding, Mrs. Simon Guggenheim gave the museum a Picasso. In the midst of the Great Depression, no less. The museum's founders and patrons were grateful for the gift (obvs) but weren't expecting anything else. 

Then Mrs. Simon Guggenheim came back to the museum with a giving vengeance! Following up the Picasso with The Sleeping Gypsy to what became great acclaim. The painting's now marked as one of the museum's greatest hits, and is considered one of the most important paintings from Rousseau's career. Mrs. Guggenheim changed up her streak of beneficence by giving in excess of $1.5 million in annual funds for the rest of her life. This allowed the museum to purchase works for its permanent collection at their discretion. 

The painting has kept a long list of haters since the fin de siecle. This happened most publicly when Rousseau tried to sell Gypsy to the mayor of his hometown, but got rebuffed. Hard. Though there's quite the whimsical bent to all the artist's work, people still have a hard time getting over the lion in Gypsy having a backwards flowing mane and a sheepish face... as in a face that looks like an actual sheep. Rousseau's only preparation for the work was going to the zoo a couple times and taking mental pictures. Should have taken actual pictures. Still, you've got to at least give the guy an A for effort.