For the art historian Taco Dibbits, director of collections at the Rijksmuseum, the answer lies in Rembrandt’s ability to penetrate to the core of his subject, no matter who or what he was painting. “Over the centuries, Rembrandt has inspired artists in different ways,” Dibbits tells me. “Something that has fascinated a lot of artists is the way he depicts different humours, different moods, different psychologies. There is such depth to his personalities: the essence of his genius is that rather than trying to make people more beautiful than they are, he depicts them as they really are. That makes his portraits immensely humane and approachable – unlike, say, classic Italian portraits, which are far more aloof and less direct. Rembrandt didn’t try to please his subjects or the viewer. With Rembrandt, you are looking at real people.”

Unvarnished

This quality of Rembrandt’s “raw truth” – to use a phrase coined by Auerbach – ensured the Dutchman’s enduring influence. And there was nobody about whom Rembrandt was more honest than himself: over four decades from the late 1620s until the year of his death in 1669, he produced a remarkable series of around 60 unsparing self-portraits. A reproduction of one of these in which he wears a beret, painted circa 1659 and now in the collection of the Musée Granet in Aix-en-Provence, is visible in the background of Penn’s photograph of Bacon, who, inspired by Rembrandt, executed more than 40 self-portraits of his own.

“Rembrandt was crucial to Bacon in terms of mark-making and the handling of paint,” explains Pilar Ordovas of the Ordovas gallery in London. “But he also provided the motivation to make self-portraits. Painting a self-portrait is one of the hardest things to do for an artist – to detach from yourself and be credible and convincing when you are not painting a stranger but yourself. Also, technically it is much harder, because you are looking at yourself through a mirror, and you cannot go around and work as you would from another sitter.”