I was interviewing several new students yesterday, and showing them and their mom my web site.  Her first comment was “I notice that in the home page photograph, the student’s arms are very high.  My children have always been taught to keep their arms low.”  There is a common misconception about arm position, from teachers and players alike.  And great harm can be done a young student by suggesting that “by sight,”  there is one optimal position for the arms.  When we approach this issue from a question of balance, we discover that the height of the arm is a constantly changing entity, and in EVERY instance, it is dependent on a connection with the weight of the arm and the role of the arm as lever to channel that weight (or proportions of it) to the string.  If we begin our positioning with an understanding of arm weight and the need to have it accessible, then the question of optimal arm height naturally resolves itself, in every position, on every string.  You can find more information about finding this equilibrium at left arm balance and at right arm balance.