The commentary translated in these pages is unusual and rare. But if the commentary is a rarity, its subject matter--the seven-line invocation of Padmasambhava--is one of the best-known prayers in the Tibetan Buddhist world. The overall significance of the Seven-Line Prayer is perhaps best appreciated in relation to a practice called guru-yoga, or "union with the nature of the guru." The purpose of guru-yoga is to purify and deepen the student's...