Probably the earliest surviving painting by Johannes Vermeer. It is very little like the characteristic style he would develop, being much influenced by the Italianate school of the likes of Caravaggio, and it is the only one of his based on mythology. In fact it is the only non-realistic painting of his we have.

The signature was destroyed by several bouts of cleaning in the twentieth century, but in 1895 it was recorded as reading J R VMeer. This is not conclusive, since there were numerous artists of very similar name around at the time. What makes me sure it is his is the nymph bathing Diana's feet. Her face is rather like that of the maid in an unquestionable Vermeer, A Maid Asleep, but as they're at quite different angles, it's actually the bronze-coloured satin garment she's wearing in both pictures that nails it.

It's a landscape of sorts. At least, it's outdoors. The goddess Diana is in the centre in a gold dress, facing right, there's a nymph squatting to wash her feet, and there are three other companions nearby. And a dog. Apparently this is the only animal in Vermeer's works. It's a typical pastoral scene of the era, without much merit. There's nothing original about the composition, and there's nothing very Vermeerian about the lighting, or the expressions on their faces, the two things that are so striking about his later paintings. It is very similar to a painting on the same subject by Jacob van Loo. Van Loo's (destroyed in 1945) dated from 1648, and Vermeer's is from about 1654. It is possible that later cleaning has damaged some of the beauties of lighting.

There's someone with their back to us behind Diana, in a glorious orange robe of classical appearance, which makes a striking contrast with the very seventeenth-century and unclassical costumes the rest of them have: the models for Diana and her other companions didn't change clothes for the artist. Sitting next to the goddess, looking down at the foot-washer, is a nymph in a red top and a blue skirt, which clashes rather oddly with the general run of golds, browns, and bronzes. The foot-washer has a muted plum-coloured skirt to go with her bronze top. A fourth companion is in black, standing behind the group, and also looking down at the toilette.

I say sitting. There's a big rock to the left, which looks like it'd be rather uncomfortable to sit on. Diana's body is near it, her hinder hand reaches back to touch it, and she is angled rather oddly. It's more as if she's thought "I'll sit down on this rock" then suddenly discovered it's not a good idea, and she'll just sort of lean. There's a spiky little plant in front of it which looks symbolic, but I can't tell if it's thistle, flowerless rose, or perhaps a very young holly. Next to the plant is this very sweet, ordinary, brown and white dog. Looking away from us. Looking, also, at the nymph's washing of Diana's feet.

I said just before that this early painting doesn't have Vermeer's characteristic tantalising facial expressions. But that dog has. Even though we can't see its face. That being turned away is a trick of his to add to the mystery. So now I ask myself, what on earth is the story with that other companion, turned right away so all we can see is a bare shoulder and back? I doubt whether that was normal composition for the age.

Diana and Her Companions, or The Toilet of Diana, or Diana and Nymphs, is 98.5 cm x 105 cm, oil on canvas, and is currently in the Mauritshuis in The Hague. It was bought at the auction of the Neville Goldschmidt collection in Paris in 1876, for 10 000 francs. He had got it from a Hague dealer Dirkens for 175 florins. (I'm afraid I have no idea how those prices compare.) Back then the name of Vermeer was worthless. A fake signature of Nicolas Maes had been added. When the real Vermeer signature was revealed it was attributed to another artist of that name, and only from 1907 has it generally been regarded as by our beloved Vermeer.

Piero Bianconi, The Complete Paintings of Vermeer, Rizzoli Editore 1967 (Penguin 1987)