Escher's work is inescapably mathematical. This has caused a disconnect between his full-on popular fame and the lack of esteem with which he has been viewed in the art world. His originality and mastery of graphic techniques is respected, but his works have been thought too intellectual and insufficiently lyrical. Movements such as conceptual art have to a degree reversed the art world's attitude to intellectuality and lyricism, but this did not rehabilitate Escher because traditional critics still disliked his narrative themes and his use of perspective. However, these same qualities made his work highly attractive to the public. Escher is not the first artist to explore mathematical themes: Parmigianino (1503–1540) had explored spherical geometry and reflection in his 1524 Self-portrait in a Convex Mirror, depicting his own image in a curved mirror, while William Hogarth's 1754 Satire on False Perspective, foreshadows Escher's playful exploration of errors in perspective. Another early artistic forerunner is Giovanni Battista Piranesi (1720–1778), whose dark "fantastical" prints such as The Drawbridge in his Carceri ("Prisons") sequence depict perspectives into complex architecture with many stairs and ramps, peopled by walking figures. Only with 20th century movements such as Cubism, De Stijl, Dadaism and Surrealism did mainstream art start to explore Escher-like ways of looking at the world with multiple simultaneous viewpoints. However, while Escher had much in common with, for example, Magritte's surrealism, he did not make contact with any of these movements.