Millais Everett, Sir John: The Vale Of Rest (1858-9)

The debate about labels in art galleries is usually clear-cut. Pro-labellers believe that there are certain things viewers need to know before they can appreciate a work of art. Anti-labellers believe that fascination should come before information, even at the risk of puzzlement – and that to interrupt the encounter between viewer and art with a wordy little sticker is a kind of vandalism.

But there are doubtful cases. A firm anti-labeller may occasionally concede that a work needs a footnote, so viewers don't go off down quite the wrong track. While a keen pro-labeller may sometimes admit that any disclosure would ruin a work's effect. Oddly, both feelings may arise with the same work.

Like this one, perhaps. Pictures tell stories, or some of them do, and the story is often what a label will tell you (unless you're familiar with it, you may not pick it up). But some pictures, of course, don't tell stories. And some pictures... well, you can't be sure if they do or not. Pictures are mute and static images. They can imply the possibility of a story without having any actual story to deliver.

What's going on here? We're in a graveyard. Night is falling. We're at that point in the evening when the sun has just sunk, and the trees go abruptly into black silhouette against the still-light sky. Beyond the graveyard wall there's a low chapel with a bell. And in the foreground of this scene, which is constructed rather like a stage set, there are two nuns.

They're Roman Catholic nuns, we gather, from the rosary that one of them holds, and they're out in this graveyard under cover of semi-darkness. One of these women is digging – or digging up – a grave, and her forearm and body strain under the weight of a shovelful. The other, her senior presumably, sits overseeing the work, clutching her rosary. Suddenly, she turns round with a look of apprehension, anguish, guilt. What on earth is going on?

Millais's The Vale of Rest was painted for an audience that liked and expected a picture to have a story. It could be a story taken from a novel, a poem, from history or even a news report. It could be a story newly made up by the artist. It could be a story that the viewer had to work out patiently from the clues provided.

The title was often a big clue. But in this case, it seems to offer only a clever and troubling irony. A graveyard is a vale of rest. But there is evidently no rest for these two women. One is burdened by strenuous physical labour. The other seems filled with deep psychological unrest. The title only returns you to the enigma of the image.

That enigma is intensified by the way each element of the scene is so highly charged. Graves. Dusk. A walled enclosure. The spooky, looming trees. Nuns. Catholics (in England then, still an object of suspicion). Sexual segregation. Religiosity. Mistress and servant, a power relationship, maybe some deeper emotional bondage. Female labour. Something being buried or exhumed. Twin wreaths. The deep, dark earth. Corpses, secrets, conspiracy, fear.

It's a picture that pulls out all the stops. It's like one of those moments in grand opera when plot, setting and music come together. The soprano is singing out in pure, hysterical defiance. An off-stage chorus of monks is to be heard chanting their endless liturgy. A great bell tolls. And beneath it all, in the lower orchestra, ominous and ever more urgent stirrings signal the approach of Fate.

But with an opera, the audience can often enjoy the ensemble without worrying about the story. With a picture like this, that's not so easy. It isn't an operatic or symphonic image, a great torrential experience in which to lose yourself. Each of its charged effects is visually distinct. It has a clear schematic structure: foreground and background, left and right. (See how the heads of the two nuns are level and symmetrical.) Its parts look like calculated clues, asking to be worked out.

And as the narrative and dramatic incitements mount up, the tension becomes almost unbearable. What is going on? If only we knew what the story was, that would break the tension. If only we knew that at least there was a story, that it made sense somehow, even if we didn't know how, that would be something. Or if only we knew that there definitely wasn't a story.

It's a picture that uses its power to conjure up and not to declare. It's like an early painting by Degas called Interior, where something dreadful is happening between a man and a woman, but we can't tell what. The fear in the scene breeds with the restless quandary of the viewer to create an air of total paranoia. Everything seems to mean something. Everything looks obscurely but menacingly significant.

And a label? It could hardly avoid the issue. It would have to break the spell, and the news that in fact The Vale of Rest has no story – so enjoy it as an exercise in pure hints and atmospherics.

Or there might be no label, which would keep you spellbound and guessing – but also keep you from fully savouring Millais's brilliantly manipulative stagecraft.

No answer, really. It's a picture where you need both to know and not to know.

The artist

John Everett Millais (1829-96) was a child prodigy. At 19, he became a founder member of the Pre-Raphaelite Brotherhood, and painted some of its classic works: Isabella, Christ in the House of his Parents, Ferdinand Lured by Ariel. These are images where clarity and proliferation of detail swamps drama. His drowning Ophelia involved endless observation on the banks of the Thames, and Elizabeth Siddal freezing in a studio bath. The Vale of Rest was almost his last good work. After that, Millais became a roaring success – also known as a sell-out.