Several exhibitions are giving Americans a chance to see the art of Tibet. An important show at the Metropolitan Museum of Art, “Sacred Visions: Early Painting from Tibet,” will unite for the first time a group of some 60 rare thangka paintings from the 11th to 15th centuries, when Buddhism was establishing itself in central Tibet. Similarly, this fall the Sackler Gallery, Washington, D.C., is showing an exhibition entitled “The Buddha's art of Healing: Tibetan Medical Paintings from Buryatia.” The way in which Tibetan illustrated texts depict healing is examined.