Complex sentence: Giacomo Carissimi (baptized April 18,1605--January 12,1674) was an Italian composer, one of the most celebrated masters of the early Baroque, or, more accurately, the Roman School of music.
Split into simpler sentences: Giacomo Carissimi (baptized April 18,1605--January 12,1674) was an Italian composer. He is one of the most celebrated masters of the early Baroque or, more accurately, the Roman School of music.