CELEBRATED Lebanese composer Mansour Rahbani who passed away following a bout of pneumonia at the age of 83, left a legacy of innovation in the music and theater of Lebanon and the Arab world. Known for his legendary collaboration with his brother Assi (who was married to Lebanese diva Fairouz), the Rahbani Brothers composed numerous songs and plays which became hugely popular with Arab audiences. Ines Weinrich, a research associate at Beirut's German Orient Institute, writes in her 2006 book on the three-way collaboration, “Fairouz and the Rahbani Brothers: Music Modernity and Nation”: Though their fans liked to say Assi and Mansour's work was inseparable - the two men did have different tendencies. Both wrote poetry -- Assi in dialect, Mansour in literary Arabic. Assi was fond of 6th-and 7th-century poetry and folk music, while Mansour preferred to compose for very large orchestras, especially toward the end of his career with Fairouz. Mansour himself wrote in Al-Wasat magazine that, when the brothers co-wrote their plays, Mansour would work on one scene, Assi the next. Then they would exchange their work for corrections. Mansour was a more adept organizer than Assi, and brought structure to their work. This was particularly important when Assi suffered post-stroke brain damage in 1972. Impatient with the rigors of teaching himself to write again, Assi dictated his work to Mansour. According to Lebanese poet Henri Zoughaib's Rahbani Brothers biography, the brothers had an impoverished childhood: their father played the oud at local coffee shops to make ends meet. Much of their work focused on themes of village life, growing up, love and patriotism. Weinrich says that in the 1940s and ‘50s, the brothers contributed to the diversification of the Lebanese music scene by introducing such new elements as rumba, foxtrot, and bossa nova to their palette of folk music and muwashahat. They made Lebanese music more international, reflecting the cosmopolitan current that was moving through the region at the time, and opened the Lebanese dialect to a wider audience. The brothers' real genius, Weinrich added, was evident at the social level - in an ability to transpose traditional Lebanese folk music to a new context. The duo wrote several acclaimed musicals, including “Season of Glory” (1960), “A Love Poem” (1973), “Petra” (1977) and “Biyaa al-Khawatem” (The Ring Seller - 1964), which was adapted on screen by Egyptian film director Youssef Chahine. Their music did change over the years. The compositions in the 1950s was very heterogeneous, Weinrich said, using many different international styles. From the late ‘50s until 1966 the music became almost exclusively Lebanese. In 1966 the brothers' work opened up to more pan-Arab themes. “The Days of Fakhr al-Din,” for instance, took the story of the 16-17th-century Lebanese emir and gave it an Arab (that is, an anti-imperialist) reading. Fairouz had been singing about Palestine since 1955, with the song “Rajaaoun” (“We will Return”), Weinrich said, but these earlier songs were more honest and realistic. They addressed loss, especially the beauty of the land, and promised to return. Like everywhere else in the region, the Rahbani brothers' work became more political after 1967. The plays in the ‘50s were like fairy tales, where the little village was a microcosm of Lebanon. In the late ‘60s, the plays moved to the city, telling stories that were less lyrical, more direct, even brutal. Fairouz and the brothers went their separate ways in 1979 - the brothers working with other female singers and Fairouz turning to her son, composer Ziyad Rahbani. Assi died in 1986 but Mansour continued to compose musical stage plays for large orchestra, including “Legacy,” “Kings of the Sects” and “Socrates.” His most recent work, “The Return of the Phoenix,” opened in the summer of 2008 and is still being performed in Lebanon.