Calendars in Books of Hours were sometimes illustrated by vignettes depicting the "labors of the months," generally rural seasonal activities, such as shearing sheep in June and mowing hay in July. Bening, whose works were highly sought after throughout Europe, is usually regarded as the last great Flemish illuminator. This book was made for a member of the Portuguese Sá family, from whom it passed to King Manuel's armorer, Alvaro da Costa, after whom the manuscript is named. Bening was especially known for sensitively rendered landscapes in full-page calendar illustrations. Such cycles had not occurred in manuscripts since their initial and singular appearance almost a hundred years earlier, in the duc de Berry's Très Riches Heures, a manuscript that inspired Bening.