An Italian composer of instrumental sonatas: primarily wind instruments as that was his chosen musical medium. These sonatas are comprised of seven to nine definite blocked sections and frequent tempo changes. The music indicates that the changes would take place by oral direction. Castello's upper registered parts (flute, violin, and cornett), and occassional bassoon parts, required virtuoso performers. A contemporary of Monteverdi -- whom he probably knew, but there is no biographical information to verify this -- Castello was an important figure in the development of the instrumental sonata form. ~ Keith Johnson