Recent nonfiction briefly noted . . .; A Swiss national treasure revisited The Plan of St. Gall: In Brief, by Lorna Price. Berkeley, Calif.: University of California Press. 100 pp. $55.

Early in the 9th Century, a group of Benedictine monks drew up a plan for an ideal monastic community, designed to satisfy practical human needs in an atmosphere conducive to spiritual devotion. The plan, preserved on vellum, was never fully executed, but intended as a model for monasteries to be built throughout the realm of Charlemagne.

Today the Plan of St. Gall is a Swiss national treasure, recognized as ''architecture of a high and complex order, and heightened by aesthetic sensibilities rare in any age.'' It skilfully blends Roman and Germanic traditions with a sophisticated understanding of variables such as internal traffic patterns and multiple uses of space. Art historian Walter Horn and architect Ernest Born collaborated to publish in 1979 a three-volume study of the Plan of St. Gall, which resolved many long-stanging scholarly questions and was acclaimed as ''one of the great feats of modern historical reconstruction.''

Now editor Lorna Price has gathered some of its highlights - including over 100 illustrations - into a single elegant volume. Artists' renderings and floor plans of areas such as the monks' cloister, bathhouse, and artisans' quarters serve better than words to convey a sense of medieval life. A book like this isn't for everyone, but it will intrigue those with a love of architecture or history. Its release coincides with an exhibition currently touring the US.