Pablo Picasso's "Dora Maar au chat" (1941) sold at auction in 2006 for $95 million.

While paging through a book of poetry by Luis de Góngora that once belonged to Pablo Picasso’s lover Dora Maar earlier this year at the Spanish national library, Professor Andrés Soria made a startling discovery: the original illustrations by Ignacio González de la Serna had been torn from the book and had been replaced with aquatints by Picasso himself.

Soria speculates that Picasso was so appalled by González de la Serna’s treatment of Góngora’s poetry — which Picasso cherished — that he ripped the images from the book and added his own illustrations as a special present for his then lover, Dora Maar. Most of the artist’s proofs in the book were later released in a livre d'artiste Picasso produced on Góngora, though two appear to be unique to his gift to Maar. The library reportedly purchased the work at auction in 1999, completely unaware of the special treasure inside.

Picasso first met Maar when he spotted her at a restaurant, engaged in a table game involving a knife. After an errant cut slashed her hand, blood rushed into her glove, which Picasso accepted as a gift, igniting what was to become one of the Spanish artist’s most tumultuous love affairs and one of his greatest inspirations. His Dora Maar au chat (1941) sold at Sotheby’s in 2006 for a heady $95 million.

The lovers split in 1946, though the two were perhaps forever changed. Commenting about the affair, Maar once remarked, "I was never just Picasso's lover. He was my owner." Picasso, for his part, claimed that she was mentally ill and sought treatment for her with famed psychoanalyst Jacques Lacan near the end their relationship.