suggested in the central panel, as large explosions in the background throw light through the city gate and spill onto the water in the panel's midground. Interpretation In the 20th century, when changing artistic tastes made artists like Bosch more palatable to the European imagination, it was sometimes argued that Bosch's art was inspired by heretical points of view (e.g., the ideas of the Cathars and/or putative Adamites or Brethren of the Free Spirit) as well as by obscure hermetic practices. Again, since Erasmus had been educated at one of the houses of the Brethren of the Common Life in 's-Hertogenbosch, and the town was religiously progressive, some writers have found it unsurprising that strong parallels exist between the caustic writing of Erasmus and the often bold painting of Bosch. Others, following a strain of Bosch-interpretation datable already to the 16th century, continued to think his work was created merely to titillate and amuse, much like the "grotteschi" of the Italian Renaissance. While the art of the older masters was based in the physical world of everyday experience, Bosch confronts his viewer with, in the words of the art historian Walter Gibson, "a world of dreams [and] nightmares in which forms seem to flicker and change before our eyes". In one of the first known accounts of Bosch's paintings, in 1560 the Spaniard Felipe de Guevara wrote that Bosch was regarded merely as "the inventor of monsters and chimeras". In the early 17th century, the artist-biographer Karel van Mander described Bosch's work as comprising "wondrous and strange fantasies"; however, he concluded that the paintings are "often less pleasant than gruesome to look at". In recent decades, scholars have come to view Bosch's vision as less fantastic, and accepted that his art reflects the orthodox religious belief systems of his age. His depictions of sinful humanity and his conceptions of Heaven and Hell are now seen as consistent with those of late medieval didactic literature and sermons. Most writers attach a more profound significance to his paintings than had previously been supposed, and attempt to interpret them in terms of a late medieval morality. It is generally accepted that Bosch's art was created to teach specific moral and spiritual truths in the manner of other Northern Renaissance figures, such as the poet Robert Henryson, and that the images rendered have precise and premeditated significance. According to Dirk Bax, Bosch's paintings often