Art of Tone Production and Physical Cause

No effect can possibly arise from the instrument without a physical cause. Each cause has a corresponding law that determines each effect. Every possibility of sound-quantity and quality, every possibility of speed in note succession and agility must rest on physical facts.
In order for these physical facts with regard to the key to be fulfilled, our employment of the requisite muscular conditions is required. These conditions involve conscious activity of the four components

1. fingers,
2. hand,
3. forearm, and
4. upperarm.

When the exact treatment needed by the key is fulfilled, each possible sound-effect can be obtained. These possible different treatments of the key can only be fulfilled by the employment of muscular-conditions.
Each key treatment is correspondingly different for each sound-kind. The muscular-conditions necessary give no evidence of their existence to the eye, meaning they are not visible during performance. The needs of the key must be fulfilled by our human playing mechanism (see Physiological Mechanics) in the most efficient way.

Tone-production is the art of drawing any kind of sound from the instrument at will, and the ability to create a variety of sounds.
Tone-production also includes the problem of agility and is hence a question of

1. mechanics,
2. physics,
3. physiology, and
4. psychology.

Keyboard Technique is an art that does not rest on mere rules but rests on physical laws which are as inexorable as those of mathematics. The art of tone-production implies implicit obedience to the laws that govern sound-excitation through movement of the piano key. An art which cannot be expressed unless we are able to muscularly fulfil the needs of the key in the most efficient way.