A rare one-off image of a monkey dangling from a vine, which has an added fanciful dimension: Picasso has etched in shadow details around the animal's body. The notion that the monkey's shadow doesn't correspond to the monkey itself reflects Picasso's interest in exploring the effects of transparency and superimposition, which photography beautifully translates.

The legendary artist's pictorial experiments with knife engravings on negatives are fully described and illustrated in Anne Baldasarri's picasso and photography, the dark mirror. He enjoyed manipulating celluloid negatives, incising them with a knife, pricking them with a pin, or painting on their surface. The experiments began informally in 1932, when Picasso was visiting the studio of his friend Brassai. He casually removed a negative from a table and began cutting into it. Transfixed by Picasso's deftness and the unusual appeal of the image, Brassai was subsequently inspired to create "Transmutations," a portfolio containing a series of nude portraits relying on the cliche-verre technique.

Picasso's marvelous experiments continued for decades. In the 1950s, he collaborated with Andre Villers on a decade-long exchange drawing on the photographer's skill and Picasso's artful paper cutouts. Villers described one session: "It's silent, except for some scraping--someone is scrawling. Picasso's at work." Subsequently, the publisher Pierre-Andre Benoit once again drew Picasso's attention to celluloid film as an engraving medium. Picasso exploited the ambiguous borders between engraving and photography, pushing the limits to give birth to a new kind imagery.