Complex sentence: Thomas Morley (1557 or 1558--October 1602) was an English composer, theorist, editor and organist of the Renaissance, and the foremost member of the English Madrigal School.
Split into simpler sentences: Thomas Morley (1557 or 1558--October 1602) was an English composer, theorist, editor and organist of the Renaissance. Arguably he was the foremost member of the English Madrigal School.