the received 'canon' of performed musical works." Since around 1980 the music of Hildegard von Bingen (1098–1179), a German Benedictine abbess, and Finnish composer Kaija Saariaho (born 1952) has begun to enter the canon. Saariaho's opera L'amour de loin has been staged in some of the world's major opera houses, including The English National Opera (2009) and in 2016 the Metropolitan Opera in New York. The classical ensemble canon very rarely integrates musical instruments that are not acoustic and of western origins, it stayed apart from the wide use of electric, electronic and digital instruments that are common in today's popular music. Visual arts The backbone of traditional Western art history are artworks commissioned by wealthy patrons for private or public enjoyment. Much of this was religious art, mostly Roman Catholic art. The classical art of Greece and Rome has, since the Renaissance, been the fount of the Western tradition. Giorgio Vasari (1511–1574) is the originator of the artistic canon and the originator of many of the concepts it embodies. His Lives of the Most Excellent Painters, Sculptors, and Architects covers only artists working in Italy, with a strong pro-Florentine prejudice, and has cast a long shadow over succeeding centuries. Northern European art has arguably never quite caught up to Italy in terms of prestige, and Vasari's placing of Giotto as the founding father of "modern" painting has largely been retained. In painting, the rather vague term of Old master covers painters up to about the time of Goya. This "canon" remains prominent, as indicated by the selection present in art history textbooks, as well as the prices obtained in the art trade. But there have been considerable swings in what is valued. In the 19th century the Baroque fell into great disfavour, but it was revived from around the 1920s, by which time the art of the 18th and 19th century was largely disregarded. The High Renaissance, which Vasari regarded as the greatest period, has always retained its prestige, including works by Leonardo da Vinci, Michelangelo, and Raphael, but the succeeding period of Mannerism has fallen in and out of favour. In the 19th century the beginnings of academic art history, led by German universities, led to much better understanding and appreciation of medieval art, and a more nuanced understanding of classical art, including the realization that many if not most treasured masterpieces of sculpture were late Roman copies