C and E

 

This combination is a major third interval and is considered consonant. It forms a somewhat brighter, even happier, sound combination than it's somber cousin, the minor third. (See C & D#.) An interesting example of both occurs at the beginning of the familiar Fifth Symphony of Beethoven. The first four notes are from a major third interval, then the next four are from a minor third interval.

Click to hear this sound as played on a piano: C & E

Below is an example of this note combination over a longer time interval.