According to the mystical point of view there is one chief root, which can be called a common cause, from which all diseases are derived, and that is disorder of rhythm. The upset of the nerves is stated by scientists to be the chief origin of all mental diseases, and their effect upon the body produces various diseases in the body. Religious people teach concentration and meditation, sitting in a prayerful attitude. The wisdom behind all this is to bring the activity of mind and body to a normal condition.

For it is the nature of activity to become more active every moment; it is the activity itself that produces energy, and the consequence is that by so producing energy, its own strength throws it out of its normal rhythm.

This one can see in the burning of the fire. The activity is little at the start; but with every moment that it bums its activity increases and culminates in the end in its utmost speed. And the speed of the beginning compared with the speed of the end will prove that it is the increase of speed of the fire which has brought about the climax, when it consumes itself.
In human nature we see the same tendency. When speaking one is inclined to speak more and more quickly, until the speed is so increased that one leaves out several words of the sentence without any intention of doing so.
So it is in walking; the pace increases with every step until a person finds himself almost running.
So it is with the imagination.
And sometimes one sees the same thing with the pulsation of the body and the circulation of the blood.

Uncontrolled increase of speed, in all its aspects, hastens the climax, and when unbalanced culminates in disastrous results.

A healer without this knowledge is a blind healer who does not know the cause of diseases; his healing is a chance; but the one who knows this is more than a physician and more than a healer. He will control his own activity, and the power of control thus gained will enable him to control the activity of others, in order to keep it normal, in which is the true health of mind and body.