RE: [Harp-L] Why use the term "perfect" to describe a perfect fourth or a perfect fifth?

[John Neff <soulchicken@xxxxxxxx>]

This is the most basic definition:
 
In classical music from Western culture, a fifth is a musical interval encompassing five staff positions (see here for more details), and the perfect fifth is a fifth spanning seven semitones. For example, the interval from C to G is a perfect fifth, as the note G lies seven semitones above C, and there are five staff positions from C to G. Diminished and augmented fifths span the same number of staff positions, but consist of a different number of semitones (six and eight).
The perfect fifth may be derived from the harmonic series as the interval between the second and third harmonics. In a diatonic scale, the dominant note is a perfect fifth above the tonic note.
The perfect fifth is more consonant, or stable, than any other interval except the unison and the octave. It occurs on the root of all major and minor chords (triads) and their extensions. Up until the late 19th century it was often referred to by its Greek name, diapente,[1] and abbreviated P5. Its inversion is the perfect fourth.
 
Peace,
John

 
> Date: Thu, 2 Jun 2011 09:23:28 -0500
> From: michaelrubinharmonica@xxxxxxxxx
> To: harp-l@xxxxxxxxxx
> Subject: [Harp-L] Why use the term "perfect" to describe a perfect fourth or a perfect fifth?
> 
> A student wants to know and so do I.
> Thanks,
> Michael Rubin
> Michaelrubinharmonica.com