Last secret magic of Renaissance art

Religion is concerned with a spiritual realm beyond the visible world. Science only accepts – for practical purposes and, if you are Richard Dawkins and others, for philosophical purposes, too – the existence of that visible world, and attempts to discover its nature and how it works. But magic is the desire to use invisible forces to change the visible world.

Works of art that we look at today in museums, as if they were solely intended for mute aesthetic contemplation, were often made for magical purposes. This is clearly true of the Ancient Egyptian Book of the Dead, but it also applies to art made thousands of years later in Europe. In Renaissance Florence, portraits of traitors were often painted on walls in public places – after one conspiracy, no less an artist than Sandro Botticelli portrayed the conspirators on the Piazza della Signoria. These were not merely "wanted" posters. They were visual curses: paintings that set out to injure their victims, to invoke malevolent magic. In a similar way, when a Venetian Doge betrayed the Republic of Venice his portrait in the Doge's Palace was blanked out. A modern regime might simply remove his picture: by preserving it over the centuries, as a blank space, Venice did something more potent and spooky.

The most famous magical images of the Renaissance were, however, more benign in their influence. 

The church of the Santissima Annunziata in Florence treasured – and still does – a miraculously painted Annunciation whose protecting powers made it, in the 15th century, more famous than anything by Botticelli. When the city was in danger it was believed to guard the populace while another magical Madonna was ritually brought into the city from the suburbs at moments of peril.