Kayotsarga is the process to search and find the root cause of all miseries and sufferings. The gross physical body is the medium for the perception of suffering or its manifestation but not its root cause. The root cause is the subtlemost body called karma sarira.
In the state of Kayotsarga, one is able to detect and identify the root cause of mundane suffering. And once this truth is known there is a fundamental change in the attitude towards the gross body.
The real enemy, the tyrant, the progenitor of all worldly suffering is the karma sarira. But until this truth is discovered, it is the poor gross body, which bears the brunt of the wrath of the sufferer.
In reality, the gross body is our ally and not the enemy; at least it could and should be made an ally in the war against the real enemy. Once the elusive real enemy is identified, all efforts must be made to liquidate it. And the gross or physical body could be our ally rather than an opponent in the war. Until this truth is realized, one does not befriend and cooperative with the physical body. The first action of alliance with the physical body is to relax it and make it free from all tensions and stresses.
To perpetuate its existence, the enemy - the karma sarira - has made elaborate preparations. Survival of the enemy is the state of bondage of the spiritual SELF and the death of the enemy is emancipation of the SELF. It is understandable that the interest of the enemy - karma - is to perpetuate the state of bondage. Having enmeshed him in its clutches, it will resort to every means to keep him enslaved. The first line of its attack is to control the functioning of the physical body - unfortunately not recognized as an ally by the spiritual self - and its strategy is to keep the body in perpetual agitation, tension and motion.
Agitation and motion are potent weapons in the armoury of the enemy. It deludes and continues the delusion so that the spiritual self is unaware of its own separate existence.
Tension produces vibrations, shock waves in the form of primal-drives, urges and impulses. The smoke-screen of the turmoil of agitation is so effective that the enemy is unseen and unrecognised. The delusion of the spiritual self is unbroken and the assertion of its authority nullified. Self-awareness is impossible under the bombardment of waves of excitation and emotion. If there was no motion, if the turmoil was somehow stopped and the calm of motionlessness achieved, the spiritual self would undoubtedly become aware of his existence, and strive for his freedom and emancipation. It is clear from the above that turmoil produced by the karma sarira is not only a plan of defence for survival but also a very potent weapon of attack. If one desires to defeat the enemy and win the war, it is obvious that the turmoil of motion is to be stopped. And Kayotsarga is the right strategy in this direction.
When all bodily movements are stopped, the Shockwaves boomerang on the enemy and shock it. The calm of motionlessness is a direct hit and it trembles for the first time. A serious breach has been created in its fortifications. The practitioner's motionlessness and subsequent self-awareness explodes the conceit of the enemy and it trembles. Its lines of assault fall in large numbers. Its armament becomes useless and the defeat commences.
The first offensive in the war against the enemy is relaxation, eliminating turmoil and agitation of the body. Keeping perfectly still, stopping all voluntary movements is an essential part of this exercise.