Ives was said to be influenced by Ralph Waldo Emerson, who wrote . . . The imitator dooms himself to hopeless mediocrity. Ives experimented with several musical innovations. We have come to identify these techniques with 20th century composition. Western musical scales consist only of half and whole tones.
Quarter tones are half of a half tone.
Most of us hear quarter tones simply as notes that are off key or out of tune. Tonality is a term describing the use of keys in a musical composition. In this system, which prevailed from the 17th to 20th centuries, a single pitch or tone is central to the work. . Ives innovations included atonal works with no key and polytonal works with many keys. Prior to the 20th century, most compositions had time signatures indicating for a distinct section of music the value assigned to a beat and the number of beats per measure.