Modern classical music is music written in the 20th century and beyond. Although much of it draws heavily on earlier forms, modern composers also experimented with rejection of long-held ideas; notably, Arnold Schoenberg questioned the traditional notions of harmony with his twelve-tone system[?], and John Cage questioned the very definition of music with his use of chance and found sounds.
... Jerónimo de Yuste[?], Spain September 21, 1558) was Holy Roman Emperor (as Charles V) from 1519-1558; he was also King of Spain from 1516-1556 -- officially as Charles I ...