The differences between the French schools lie in the posture of the arms, shape of the hand, and musical aesthetics. The traditional French schooling lets the player lightly rest the right arm against the harp, using the wrist to sometimes bring the hand only away from the string. The left arm moves more freely. Finger technique and control are the emphasis of the technical approach, with extensive use of exercises and etudes to develop this. Two very influential 20th-century teachers of this approach were Henriette Renié and Marcel Grandjany, who studied with Alphonse Hasselmans. The other major French school is the Salzedo school, developed by Carlos Salzedo, who also studied with Alphonse Hasselmans at the Paris Conservatoire. Salzedo's technique generally calls for the arms to be held horizontally and emphasizes the role of aesthetic hand and arm gestures after the string has been plucked: "Each of the thirty-seven tone colors and effects of the harp calls for a gesture corresponding to its sonorous meaning."