"But that first arcanum that a stranger penetrates after staying for a time in a monastery--the slow and cumulative spell of healing quietness--has lost none of its magic." Patrick Leigh Fermor wrote these words in A Time to Keep Silence ($12.95 pb), first published in 1957 and now available in a new edition. If a book can literally be a gem, Fermor's eloquent chronicle of his retreats to monasteries in France and Turkey is a priceless jewel indeed.