'There is no room for originality in thangka painting," says Yumyo Miyasaka. "The iconography, the colors, even the way you hold the brush -- everything must be done just so." Self-expression is not the goal here; the pictures are an aid, a tool for meditation. The self is what you are trying to lose.

Each shade of color must be separately ground and mixed in its own pot from natural materials.

Buddhist paintings came to Tibet with the religion. Buddhism first reached there in the seventh century, but its practice remained limited to the royal court. Conflicts with adherents of the native Tibetan Bon religion caused a temporary eclipse after the mid-ninth century.

From the beginning of the 11th century a new diffusion began, this time with a more popular appeal. Tibetans traveled in large numbers to the great universities in the Buddhist Pala Empire of eastern India (eighth-12th centuries), where they populated whole colleges in present-day Bengal and Bihar and copied libraries of texts and icons to take back to Tibet.

The Pala Empire with its temples and universities was destroyed by the Muslim invasions of the 13th century, and no examples of Indian Buddhist painting survived -- except in Tibet, where they became the models for Tibet's own monastic painters.

The tradition did in fact undergo some stylistic development over the centuries, absorbing influences from Nepalese, Central Asian and Chinese Buddhist art, but its line of transmission continued unbroken to and through the catastrophe of the 20th century. Today in Dharamsala, and wherever Tibetan exiles practice their religion, thangka painters continue their work.

Thangka vary in their subject matter from portraits of Buddhist saints to giant mandalas that chart the structure of the entire universe. Even a simple portrait, however, is far from simple. Besides the figure itself, the setting, background, architectural elements and subsidiary figures are executed in great and specific detail. Each element has its own symbolic, didactic import; all together they express a transcendent idea.

An important point about thangka, in contrast to mural paintings, is their portability. Painted on thin cotton or linen, they are kept rolled or folded, and brought out when needed for instruction, study or meditation.

Meditation in esoteric Buddhism is a different practice from the koan conundrums or just-sitting of Zen. The esoteric adept focuses on the image in all its conceptual complexity, seeking to visualize and make each of the symbolic details with its inherent meaning real in his or her own mind, to the point where the mind merges with the painting and through it with the universe. It is a challenging practice that requires enormous discipline and concentration. It is not for everyone.

This is a key point. Esoteric means secret, hidden. There is knowledge so deep and so awesome that only a trained mind can encompass it. To the ignorant an esoteric painting or a text may just be meaningless; to the half-wise it may actually be dangerous. The devotees must learn from the adepts who have gone before them. When the time is right, the teaching, whether text or image, will be revealed. Thus each adept gathers a personal collection of texts and images as his or her practice progresses, and important ones are passed from master to disciple through many generations.

From a practical standpoint this portability is what has enabled a certain number of Tibet's once-vast treasure of paintings to survive the invasion, war and systematic vandalism of recent decades.

The creation of a thangka begins with the preparation of the canvas, a thin sheet of cotton or (less often) linen fabric. The material is stretched tightly on a frame and sized with a mixture of chalk or clay bound with animal glue. The size is applied to both sides of the cloth, filling in the spaces of the weave and providing a smooth surface for the paint.

Preparation of the pigments is one of the most laborious and painstaking stages. Minerals such as malachite, azurite and lapis lazuli, plant and animal materials such as indigo and cochineal, must be carefully ground to exactly the right fineness. The powders are mixed with water and warm glue to the desired consistency.

Colors cannot be mixed on a palette as oil paints are, so each of the dozens of different shades must be mixed separately in its own bowl. As the paint cools and dries out it must be judiciously wetted and rewarmed until the color is used up. Since it's difficult to get exactly the same shade twice, a sufficient amount for the painting must be made beforehand.

The painting itself begins with outlining the entire composition in black. The artist then fills in one color at a time, beginning with the deepest blues and greens and working up to the bright reds and yellows. The shading with layers of different colors can be quite elaborate, but each color must dry completely before another color can be applied. Surface details of scrolling, drapery, facial features and so on are then outlined in black or indigo.

The final stage is the ceremonial painting in of the eyes of the main figure, consecrating and bringing the entire painting to life.