I visited the mammoth exhibition The Genius of Rome 1592-1623, at the R.A. in 2001. Now I find nine years later that I've been labouring under a delusion: a portrait of Guido Reni that I thought was painted by his Bolognese compatriot Domenichino, is, in fact, a self-portrait.
How did I discover the truth? I stopped by the Whitfield Gallery's web site to find out details about the summer Caravaggio: Friends and Foes exhibition. It was there that I learnt the following detail: conclusive evidence has been found that Domenichino's so-called portrait of Guido was painted by Guido himself, probably about 1602 just after Domenichino and another painter, Francesco Albani, had joined Reni in Rome.
According to the Whitfield site the painting was sent to Bartolomeo Coriolano round about 1621- documented by a letter of 2nd April 1621 attached to the back of the unlined canvas, with its original stretcher. In the section on portraiture in The Genius of Rome, it was catalogued as by Domenichino, something I've believed for nearly a decade.
The portrait has similar features to a portrait of Guido by Ottavio Leoni, in a drawing of 1614, and the letter, until recently attached to the back of the unlined canvas, says that the artist owned a small moustache- as he indeed does in the painted portrait and the Leoni drawing. The letter stuck to the canvas obscured an inscription stating that Guido, son of Daniele Reni and Ginevra de Pozzi, painted it. In fact, the inscription became visible under infra-red photography, thus further confirming- as implied in the letter- that this is Guido's own self-portrait to be sent to his mother Ginevra back in Bologna. There are other reasons, mainly stylistic, confirming Guido's own hand; Whitfield's liken the brushwork to Reni's portrait of his mother- more on the gallery website.
What an exciting and fascinating revelation. Now I come to think of it, why would Domenichino have wanted to paint Reni? It's true that some of the biographers- probably Malvasia- said they were friends in the monastery of Santa Prassede, but the disciplined Domenichino became increasingly irritated with Reni – a compulsive gambler-and Albani who played card games late into the night. Eventually, Domenichino moved from Santa Prassede to quieter quarters.
There's another dimension to this case. Reni's S/P is painted over a copy of Barrocci's Stigmatization of St Francis. This fits, as Reni's protector at Santa Prassede, Cardinal Sfrondato, hankered after a Barrocci painting.