It has been said of Gustave Moreau's work that it was an extension of Romantic art. And yet he was not a painter of drama so much as of the image: that of a moral confrontation experienced on a personal level – for example, in the Rouen painting, the sense of distance from the murder that has been set in motion. In addition, the painter uses a universal language – that of the great Renaissance masters, particularly Michelangelo and Leonardo – through myths that are no less universal.  

Rouen's Diomedes devoured by his horses is a perfect example of this approach, even if – it has to be admitted here – it was not Moreau's favourite painting. He wrote to the curator of the Musée de Rouen, ‘I would have wished, sir, to have been able to respond to your invitation in a more satisfactory manner, by sending you a larger and more accomplished picture (…)’. His subject here is based on one of the Twelve Labours of Hercules, where the Greek hero sent the horses of Diomedes to devour the king himself, who had the regrettable habit of feeding them on human flesh. The horses are inspired by the art of da Vinci and the antique hero by the drawings of Michelangelo, while the setting is taken directly from drawings by the great Italian master Piranesi.

The result is an astonishing work that could even be described as absurd, in that its meaning may easily elude the viewer. This is because the painter seems to illustrate highly personal ideas, straight out of his dreams, with a language intended to be universal. Moreau sought both a magic drawn from his own visions and a ‘purely visual art’ which, in his words, ‘would be the most penetrating, the most profound, the most sublime expression of the visual idea.’

In other words, Moreau's art is a kind of mannerism in Romantic art that is perhaps too attached to form — Degas spoke of ‘these gods wearing bracelets and watches’ — but in this way creates symbols. But when people tried to link his art with Symbolism in literature, Moreau objected, finding this view ‘stupid and unjust’. The fact remains that his art opened up new paths, because it seemed like a possible breakaway, reconciling the expression of highly personal ideas with a conceptual language. This new path was to inspire Abstract art: a direction that Moreau in fact took at the end of his life.