[AX7221]

The pattern of tones and semitones may look arbitrary, and to me i guess they do. The way i look at it is somehow (the greeks i believe) figured out a way (circle of 5ths i assume) to sort've "optimize" the seven note scale. for example for 6 out of the 7 notes of the scale you can play either a major or a minor chord without playing a note out of key, which is a very elementary and good sounding chord. So by picking this pattern for the diatonic scales the scales become very useful, and i think that's why they're so popular. (that's a question i used to think about (where did this pattern come from?) so i figured i throw my answer out there in case anyone was wondering the same thing - or if im mistake please correct me)