painting, which can be seen in the International Museum and Library of Music of Bologna, is anonymous and is thought to depict Vivaldi due to its strong resemblance to the La Cave engraving. During his lifetime, Vivaldi was popular in many countries throughout Europe, including France, but after his death his popularity dwindled. After the end of the Baroque period, Vivaldi's published concerti became relatively unknown, and were largely ignored. Even his most famous work, The Four Seasons, was unknown in its original edition during the Classical and Romantic periods. Vivaldi's work was rediscovered in the 20th century. Works A composition by Vivaldi is identified by RV number, which refers to its place in the "Ryom-Verzeichnis" or "Répertoire des oeuvres d'Antonio Vivaldi", a catalog created in the 20th century by the musicologist Peter Ryom. Le quattro stagioni (The Four Seasons) of 1723 is his most famous work. Part of Il cimento dell'armonia e dell'inventione ("The Contest between Harmony and Invention"), it depicts moods and scenes from each of the four seasons. This work has been described as an outstanding instance of pre-19th-century program music. Vivaldi wrote more than 500 other concertos. About 350 of these are for solo instrument and strings, of which 230 are for violin, the others being for bassoon, cello, oboe, flute, viola d'amore, recorder, lute, or mandolin. About forty concertos are for two instruments and strings, and about thirty are for three or more instruments and strings. As well as about 46 operas, Vivaldi composed a large body of sacred choral music, such as the Magnificat RV 610. Other works include sinfonias, about 90 sonatas and chamber music. Some sonatas for flute, published as Il Pastor Fido, have been erroneously attributed to Vivaldi, but were composed by Nicolas Chédeville. Catalogues of Vivaldi works Vivaldi's works attracted cataloging efforts befitting a major composer. Scholarly work intended to increase the accuracy and variety of Vivaldi performances also supported new discoveries which made old catalogs incomplete. Works still in circulation today may be numbered under several different systems (some earlier catalogs are mentioned here). Because the simply consecutive Complete Edition (CE) numbers did not reflect the individual works (Opus numbers) into which compositions were grouped, numbers assigned by Antonio Fanna were often used in conjunction with CE numbers. Combined Complete Edition (CE)/Fanna numbering was especially common in the work of Italian groups driving the mid-20th-century revival of Vivaldi, such