The foot

To most balletgoers, the aristocratic foot of the dancer is the distinguishing feature of classical ballet.  Strong and supple, and as sensitive as a hand, the foot is used by the dancer in a manner that, to the eye of the observer, departs distinctly from the ordinary mechanics of movement.

To a dancer the feet are servants of the first rank.  Like the tiny feeder roots of a tall strong tree, on which the health and well-being of every leaf and branch depend, the feet are a source not only of strength and support, but also of propulsion and shock absorption and, most importantly, of perception.  Sensations relayed from the foot inform the rest of the body of the level of its support, its trajectory, its orientation to space, and countless subtleties that are reflected instantly in every movement.  It is no exaggeration to say that the quality of a dancer's movement is directly related to the level of sensitivity in the use of the feet.

Inside Ballet Technique: separating anatomical fact from fiction in the ballet class by Valerie Grieg. 1994.  Page 95.