A MEDIEVAL BOOK OF SEASONS <i> by Marie Collins and Virginia Davis (HarperCollins: $30)</i> .

“Sumer is icumen in/Lhude sing, cuccu!” wrote the anonymous medieval poet, and so say all of us! In Chaucerian, of course, sumer is spring, and while our own March harbinger is more smog-alert than cuckoo-tweet, there is still an atavistic quickening of the blood round about now, tracing back to a less artificial time. In the Middle Ages, lives were bound to the cycles of nature, as these splendid selections from contemporary Books of Hours and illuminated manuscripts remind us. (Above, sheep being driven to pasture.) Spring was the favored season, abounding in rituals of renewal, celebrations, pilgrimages. (Note on previous incarnations: It wasn’t all fun and games. Overwhelming odds were that you were no Lord or Lady but a paisan , laboring from sun to sun and vulnerable to wars, plagues and common but incurable ills; even King Henry V died of a touch of dysentery. Lhude sing, cuccu!)