Bosch - A brief history
Bosch's pictures have always fascinated viewers, but in earlier centuries it was widely assumed that his diabolic scenes were merely to amuse or titillate. The Spaniard Felipe de Guevara complained in the earliest account of Bosch's art, written about 1560, Most people regarded him as merely 'the inventor of monsters and chimeras'.
In our own century, however, scholars have come to realize that Bosch's art possesses a more profound significance, and there have been many attempts to explain its origins and meaning. His name is frwequently linked with Salvador Dali. For others, Bosch's art reflects esoteric practices of the Middle Ages, such as alchemy, astrology or witchcraft.

From "The Complete Painting of Bosch" - Walter Bosing