The generic terminology for Haydn's early music reflected a period of stylistic and societal flux, and what constituted a "divertimento" was not always clear even to Haydn himself, who retitled some of his works when he cataloged them at a later date. Nevertheless, conductor Manfred Huss and his Haydn Sinfonietta Wien get a good grip on an involved subject in this five-disc set and present a good deal of highly enjoyable and in many cases largely unknown music to boot. The set makes an excellent purchase for those seriously interested in the early part of Haydn's career and in the formation of his style: you can hear him working out the compact humor of his mature works step by step in many of these little works. Right from the Divertimento a cinque in G major for two violins, two violas, and "basso," Hob. 2/2, there is a thematic economy that diverged from the basic galant style of the music. You also get an insight into the purposes for which Haydn wrote his early works. Some of these pieces were called Feldparthien, or field suites; what seems to define them stylistically is the use of winds and of hunting-horn motifs in the thematic material, treated by Haydn with his characteristic imagination. The ones that Haydn actually called divertimenti include strings (the group here often includes a pair of instrumentalists per part); they are close to the pieces called symphonies, but bear marks of incidental use. They are often in five movements, with a pair of minuets surrounding a central slow movement. Huss' flexibility in considering what constitutes a divertimento allows for the inclusion of a variety of works such as the Violin Concerto in C major, Hob. 7a/1, not conventionally placed with the divertimento group but stylistically very much part of it. There's also an ersatz (and anonymous) divertimento formerly attributed to Haydn but easily detectable as a fake; it includes the so-called St. Anthony Chorale on which Brahms wrote his Variations on a Theme by Haydn. The Haydn Sinfonietta Wien clearly enjoyed the entire project, and Huss does well to place emphasis on the brilliant finales, enlivened by buzzy blaring from natural horns. Five discs of early Haydn may be a lot for many listeners, but the price is attractive, and this should find an audience beyond a specialist listenership. The presence of veteran British authentic-performance violinist Simon Standage in the violin concerto is another plus.