Like anybody who has ever visited Paris, I have seen the Mona Lisa. That's to say, I have stood in the room where it hangs and have looked long enough to be struck by how small it is, to be slightly underwhelmed by it in general, and to wonder why, of all the world's paintings, this became the most famous.
After that, I mentally ticked another compulsory tourist experience off my to-do list and left, thinking, been there, done that, decided the official T-shirt was too expensive.
But had I truly seen Da Vinci’s masterpiece? Or to the extent that I had, might I have seen it just as well by staying at home and looking at reproductions?
I don’t know the answer to that, exactly. And the Mona Lisa is anyway an extreme example, because even if you can get a clear view, through the heads of the people in front of you, and then through the protective glass, it will still be difficult to penetrate the layers of celebrity around the picture and see the actual thing.
But what of less exalted masterpieces – the ones you can have to yourself in a gallery, at least temporarily, on a wet weekday afternoon? How long and hard should you study those before you can honestly say you’ve seen them? A minute? An hour? Years of repeat visits?
I don’t know that either.
But what set me thinking about it was the latest instalment of a now annual event, Slow Art Day, which takes place all over the world this Saturday, April 14th.
The general idea of the movement is to persuade people to take a longer look at art.
More specifically, it tends to involve guided tours wherein participants spend five, or at most 10, minutes looking at each of several works and then discussing the experience.
This is a bigger challenge than it sounds. Five minutes isn’t much.
But in practice, these days, it’s hard to look at anything except your smartphone for that long. Just observe other people next time you’re in a gallery. Even better, observe yourself.
If you’re like me, when approaching any work of art, the first thing you’ll have to do is resist the urge to consult the little information panel before the actual picture.
You know you should be able to appreciate a painting as a purely visual experience, devoid of supporting text. But it’s still an effort.
So after exhausting your small repertoire of different ways to look at the artwork – tilting your head to one side, squinting, etc – you soon succumb to reading the biographical note. And this is always a relief, although you may try to make it look like an afterthought.
Then, perhaps nodding in recognition that the work is by Gauguin (you knew that, of course), you glance at the painting again as if to confirm something. So that was the year before he died, you think.
Or maybe you’re looking for evidence of syphilis in the brush technique Then you move on to the next painting.
And after all that, you probably still have change out of a minute.
In fact, if you can manage a minute of staring at a picture, you’re a more committed art lover than most.
The Louvre, for example, has measured the typical person’s engagement with the Mona Lisa at 15 seconds.
Other surveys suggest that’s about the norm for paintings in general, although New York’s Metropolitan Museum, where they must get a better class of customer, suggests the average there is a leisurely 32.5 seconds.
If the Slow Art movement persuades us to linger, however, what should we hope to experience? Well, George Bernard Shaw set the bar high. "You use a glass mirror to see your face," he once said, "you use works of art to see your soul".
Fanciful as that sounds, Shaw was qualified to comment. He spent much of his youth visiting the National Gallery of Ireland and claimed it provided the only real education he received in this country. He was sufficiently grateful to become one the institution's greatest benefactors in return. You can emulate Shaw, and practise the general principles of the Slow Art Movement, any time you like, subject to opening hours.
As for Slow Art Day 2018, the National Gallery of Ireland will mark the occasion with a tour at 1.30pm this Saturday.
The guide is Mary Dowling who will discuss, "slowly and mindfully", works by Caravaggio, Jack B Yeats, Louis le Brocquy, and Joseph Walsh.
I’m told she may also add a fifth picture, an as yet unspecified “portrait”. If Shaw is correct, it may be of your soul.