Oxford Companion to Music says 4th and 5ths are perfect because they have a "certain hollowness" other intervals do not. Grove's Dictionary of Music says "Intervals which have no alternative major and monor forms, but become augmented or diminished when enlarged or reduced by a semitone." "The perfect fifth, ration 3:2 is a very good, though not absolutely perfect, consonance. Of all the intervals less than an octave the fifth is the most important, because it is the most sharply defined of them and therefore has the most influence on intonation. It is the interval between the tonic and its dominant or subdominant." "The perfect fourth, ration 4:3 is the inversion of the fifth, i.e. the difference between an octave and a fifth. Among intervals less than the octave it is second only to the fifth in smoothness and definition." I would suspect the fact that fourths and fifths are nearly beatless, or beatless, might enter, also into the notion of "perfect". les bartlett houston ________________________________________________________________ YOU'RE PAYING TOO MUCH FOR THE INTERNET! Juno now offers FREE Internet Access! Try it today - there's no risk! For your FREE software, visit: http://dl.www.juno.com/get/tagj.
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