In fact, however, matter and mind cannot be experienced separately from each other because they are interdependent, interconnected. Exploring one is bound to involve an exploration of the other. Neither can be fully understood without the other. If in the name of kayanupassana one sits with closed eyes and simply names or imagines the different parts of the body, such a person is far away from the correct practice of Vipassana, from the direct exploration of truth. Therefore awareness of physical sensation is indispensable to the practice of kayanupassana.
Sensations exist, of one type or another, at every moment on every part, every atom of the body.
One must develop the ability to feel them consciously in order to understand the entire truth of the body. Sensations can be experienced only within one's body, and the reality of body can be experienced only by means of sensations. Sensation overlaps the two fields of mind and matter. For this reason observation of sensation, as we shall see, is a way to explore the mental-physical phenomenon in its entirety. In the practice of kayanupassana, observation of sensations will enable the meditator to experience directly the changing nature of the physical structure.