Art by Hieronymus Bosch

Bosch's paintings are so strange, densely populated with hybrid creatures, surreal torments, and impossible architecture, that they remain genuinely hard to fully explain even after centuries of scholarship, and his most famous work, The Garden of Earthly Delights, is still argued over: is it a warning about sin, a fantasy of paradise lost, or something closer to an alchemical or astrological text rendered in paint. He was a member of a religious lay organization, the Brotherhood of Our Lady, in his hometown of 's-Hertogenbosch, which sits oddly next to how unhinged and nightmarish his imagery could get. Major retrospectives marking 500 years since his death, in Den Bosch and at the Prado in 2016, drew record crowds still trying to work out exactly what he meant.