In the most general form, activities that describe music as an art form or cultural activity include the creation of musical works (songs, tunes, symphonies, etc.), criticism of music, research on music history, and aesthetic assessment of music . Ancient Greek and Indian philosophers defined music as tones arranged horizontally as melody and arranged vertically as harmony. Sayings like "harmony in various fields" and "this is the music in my ears" point to the notion that music is usually orderly and sounds pleasant. But the 20th-century composer John Cage thought that any sound can be music. For example, he said: "There is no noise, only sound."