Manny- Maybe you know the answer to this... While doing my daily warm ups this am, I went to Arban lip slurs. As I was doing them, my mind began to wander ("...me of little discipline") and I noticed that Arban does not make use of the 123 combination. I never noticed this before. One could add it in at the beginning and at appropriate places in the chromatic series I assume, but, there must have been a reason he left it out (other than it's not in tune... 1 & 3 are bad and he uses that). When my corners began their protest, I decided to let them win and give them a rest and see if I could look it up in the text. There is nothing there. Any idea why? Ok...back to it.