Thousands of visitors to the Art Institute have gazed at Picasso’s Mother and Child (1921), prominently displayed on the third floor of the museum’s Modern Wing, and assumed that the plump baby extending its right arm skyward is trying to touch the mother’s face. But that’s not what the artist originally intended. This secret was revealed in 1968, when a representative from the city traveled to France to personally thank the aging Picasso for his sculpture that stands in Daley Plaza. During the visit, the envoy showed the artist a catalog of the numerous works of his in the Art Institute’s collection. Upon seeing Mother and Child, Picasso retrieved an old canvas from the recesses of his studio and dusted it off for his guest to see: It showed the partially cut-off figure of a seated man. In an early version of Mother and Child, the artist explained, the man was dangling a fish above the infant’s head. The fish and the man’s arm and hand, which Picasso eventually painted over, can still be seen with an infrared scan.

Hidden figures, it turns out, aren’t uncommon for Picasso. Infrared scans also show a ghostly woman underneath The Old Guitarist, the defining piece of his gloomy Blue Period. He often painted over his works as they took on new meaning to him. “A number of our Picassos have things underneath them: abandoned compositions or other figures,” says Allison Langley, painting conservator at the Art Institute. “He was boundlessly playful and prolific.”