As one of the most prominent composers during a period when a Russian musical identity was being shaped by numerous writers and musicians, Modest Mussorgsky became famous for his atypical compositions, which often flew in the face of established European tradition. One of the most unique composers of his time, Mussorgsky's works took great inspiration from Russian history, folklore, and took cues and arrangements from classical, traditional Russian music and works. Unlike numerous composers before him, Mussorgsky used his talent to begin the process of carving out a uniquely Russian musical identity that would inspire many composers to come.
As a member of an incredibly rich and prominent family, Mussorgsky was chosen to continue his family's tradition in the military. However, music was always important to him, and his encounters with several geniuses, including Borodin, helped push him towards his unique composing identity. As a member of the famous five Russian composers of his time, dedicated to breaking with the established tradition of mainland Europe, Mussorgsky's works reached a wide audience. He was, however, considered a 'radical' for his favorable view of the weak and poor, and his numerous works clashing with the establishment and militaristic power.
Plenty can be said about Mussorgsky, but so much can be learned through his beautiful works. Originally written as a piano suite, Pictures at an Exhibition as been rearranged and performed countless times and has become one of Mussorgsky's most famous works. It's certainly my favorite, and one of my favorite classical works ever (first part of several) -
Mussorgsky's only finished opera, Boris Gudonov, is often considered his best work. A rejection of the mainstays and conventions of German and Italian opera, Gudonov was not without its critics - many mainstream composers (including Tchaikovsky) derided it, and conservative commentators and friends of the Russian court were very vocal about their distrust of the composer and his aims.
One of the greats, definitely!