Join renowned Yale Professor Boris Berman as he explores the many variables of touch are weight, mass, and speed of attack. Weight and mass, though related, are not the same. Weight refers to the heaviness or lightness that a pianist chooses to deliver to the fingers at the attack. In order to play more heavily or more lightly, you must know how to channel the full weight of the body before measuring the degree of weight poured into a given touch. Mass, on the other hand, refers to how much of the body is involved during a given attack. You can activate different levers from smaller to larger in different combinations in order to achieve different articulations. Finally, the speed with which you activate the key can influence the character of the sound. Berman considers these variables separately, and then in combinations, demonstrating their influence on sound production in various passages from the repertoire.