issued a tract to coincide with the exhibition denouncing Dalí as "the ex-apologist of Hitler... and friend of Franco". In December 1949 Dalí's sister Anna Maria published her book Salvador Dalí Seen by his Sister. Dalí was angered by passages that he considered derogatory towards his wife Gala and broke off relations with his family. When Dalí's father died in September 1950 Dalí learned that he had been virtually disinherited in his will. A two-year legal dispute followed over paintings and drawings Dalí had left in his family home, during which Dalí was accused of assaulting a public notary. As Dalí moved further towards embracing Catholicism he introduced more religious iconography and themes in his painting. In 1949 he painted a study for The Madonna of Port Lligat (first version, 1949) and showed it to Pope Pius XII during an audience arranged to discuss Dalí 's marriage to Gala. This work was a precursor to the phase Dalí dubbed "Nuclear Mysticism," a fusion of Einsteinian physics, classicism, and Catholic mysticism. In paintings such as The Madonna of Port Lligat, The Christ of Saint John on the Cross and The Disintegration of the Persistence of Memory, Dalí sought to synthesize Christian iconography with images of material disintegration inspired by nuclear physics. His later Nuclear Mysticism works included La Gare de Perpignan (1965) and The Hallucinogenic Toreador (1968–70). Dalí's keen interest in natural science and mathematics was further manifested by the proliferation of images of DNA and rhinoceros horn shapes in works from the mid-1950s. According to Dalí, the rhinoceros horn signifies divine geometry because it grows in a logarithmic spiral. Dalí was also fascinated by the Tesseract (a four-dimensional cube), using it, for example, in Crucifixion (Corpus Hypercubus). Dalí had been extensively using optical illusions such as double images, anamorphosis, negative space, visual puns and trompe-l'œil since his Surrealist period and this continued in his later work. At some point, Dalí had a glass floor installed in a room near his studio in Port Lligat. He made extensive use of it to study foreshortening, both from above and from below, incorporating dramatic perspectives of figures and objects into his paintings. He also experimented with the bulletist technique pointillism, enlarged half-tone dot grids and stereoscopic images. He was among the first artists to employ holography in an artistic manner. In Dalí's later years, young artists such as Andy Warhol proclaimed him an