Anything can be an image, but can anything be an icon?

It's one of many religious mysteries to puzzle over for the next few months at Imprinting the Divine: Byzantine and Russian Icons from the Menil Collection. The exhibition, curated by Annemarie Weyl Carr, is accompanied by a gorgeous catalogue and runs through March 18, 2012.

Deceptively simple but unmistakably vibrant, the show offers viewers a concentrated experience of a mode of art that may look like other forms of Christian painting, but which was imagined to be not representation, but a religious encounter.

Numbered among the many riches of the Menil is one of the most nationally — and even internationally — important collections of Christian icons. The collection contains representative works from the Byzantine covering roughly twelve centuries of icon-making from Greece, Russia, and the Balkans.

But what is an icon? The term seems to refer to anything from a movie star to a clickable image on a computer screen. Linette Martin's rather useful Sacred Doorways: A Beginner's Guide to Icons, which is available in the Menil Bookstore, offers up the image of the door as a way of understand why an icon is not an image.

Standing before an icon, there is a two-way exchange. You look at the icon, and it is as if the icon looks back and a door has opened up from the secular present into a sacred past, where religious events are not history, but in some sense are eternally ongoing. The icon is a way of making contact.

For instance, imagine you are now standing before "Saint George and the Dragon," an impressive 16th-century Cretan wood panel, with George on his white horse wielding a deceptively slender spear that is thrust in heart of the dragon. Sure, it's just tempera and gold leaf in front of you. The scene no doubt looks less realistic than other depictions.

Compare that with an image of the same scene by the great Peter Paul Rubens. The realism and drama of Rubens might take us closer to the idea of a fight with the dragon; you can almost feel the steam of exertion in the warrior's flowing cape or the carefully articulated mane of his galloping horse.

Mysterious experience of intimacy

The job of the icon, however, was not to create the vicarious thrill of action, but to bring viewers closer to the event as a mysterious experience of intimacy with divinity.

In spite of what may seem odd about these works — the elongated faces, the odd colors, the almost-cubist perspectives — much will be familiar. Not only Saint George, but the archangels Michael and Gabriel, the Virgin Mary, saints and soldiers and scenes from the life of Christ.

The 15th-century Byzantine "Entry into Jerusalem" offers a particularly interesting blend of the stark features of iconic art and a complex scene of action. Christ rides a white donkey into the city, outside of which a crowd of vividly garbed citizens has emerged to greet him. Above, children play in a tree — two even struggle with one another on a hill. Divinity may be coming to town, but even in the world of the icon, boys will be boys.

Similarly impressive, if wholly static, is the extraordinary 14th-century Byzantine "John the Baptist." Incredibly textured twists of hair dominate the image. The saint's beard and the fur of his garb remind us of his time in the wilderness, as does the ruggedness of his body. But the delicately upturned hand and meditative gaze speak to his communion with immortality.

Russia, particularly Novgorod, was home to a flowering of icon culture. Recognizable as iconic and with a strong family resemblance to the Byzantine manner, the scale and texture of the Russian work is distinct enough to be noticeable.

I found myself staring quite a while at the "Raising of Lazarus." Behind Christ and a crowd of citizens, a serious of odd stony structures rise up which look like cities merging into mountains. Lazarus peers out from a dark hole in this midst: mummified, but his eyes open and his face young with life.

Seeing all these objects together, with their extraordinary sense of vertical length, their gold backgrounds, and their often-vivid colors, one feels transported. But just one glance at the surfaces of tempera and gold leaf cracking reveals intense fragility.

Many icons are made on incredibly slender pieces of wood. Many were meant to be portable, unlike the large structured pieces for houses of religious worship. These little windows to divinity are shockingly vulnerable to transport.

Transitory nature of icons

I was especially struck by the transitory nature of icons that otherwise aim at eternity, because I am still in mourning for the magnificent frescoes at the Byzantine Fresco Chapel, which will leave Houston in February to return to Cyprus. How easily the icons might have been destroyed or sold off on the black market, never to be seen again, if Dominique de Menil had not rescued them.

I know the right thing is happening: The return of the frescoes to Lysi, from which they should never have been taken. The 20-year loan that resulted from the Menil's recovery and creation of this chapel to house the frescoes has been a great gift to the city of Houston.

There couldn't be a better time for Imprinting the Divine, since it offers us all a way of thinking about the extraordinary experience one has in the Byzantine Fresco Chapel. Icons are also about what is recognizable. All figures in this art should be immediately identifiable by virtue of their qualities, scenes, or even props.

Think of Saint Catherine of Alexandria with her iconic wheel. It's like a great code unfolding before you. Once you know it, you learn to speak the language.

The Byzantine chapel has been, for me, a kind of sacred site, part of what makes Houston recognizable as the city in which I live. Since frescoes must leave, I just might have to step through the door of the icon and follow it back.

Cyprus, here I come.