An illusory mind tends either to regard body as Self and to yearn after its material interests, or to believe mind dependent on soul as Ego. Those who are given to sensual pleasures, consciously or unconsciously, bold body to be the Self, and remain the life-long slave to the objects of sense. Those who regard mind as dependent on soul as the Self, on the other hand, undervalue body as a mere tool with which the soul works, and are inclined to denounce life as if unworthy of living. We must not undervalue body, nor must we overestimate mind. There is no mind isolated from body, nor is there any body separated from mind. Every activity of mind produces chemical and physiological changes in the nerve-centres, in the organs, and eventually in the whole body; while every activity of body is sure to bring out the corresponding change in the mental function, and eventually in the whole personality. We have the inward experience of sorrow when we have simultaneously the outward appearance of tears and of pallor; when we have the outward appearance of the fiery eyes and short breath, we have simultaneously the inward feeling of anger. Thus body is mind observed outwardly in its relation to the senses; mind is body inwardly experienced in its relation to introspection. Who can draw a strict line of demarcation between mind and body? We should admit, so far as our present knowledge is concerned, that mind, the intangible, has been formed to don a garment of matter in order to become an intelligible existence at all; matter, the solid, has faded under examination into formlessness, as that of mind. Zen believes in the identification of mind and body, as Do-gen[FN#180] says: "Body is identical with mind; appearance and reality are one and the same thing." Bergson denies the identification of mind and body, saying:[FN#181] "It (experience) shows us the interdependence of the mental and the physical, the necessity of a certain cerebral substratum for the psychical state-nothing more. From the fact that two things are mutually dependent, it does not follow that they are equivalent. Because a certain screw is necessary for a certain machine, because the machine works when the screw is there and stops when the screw is taken away, we do not say that the screw is equivalent of the machine." Bergson's simile of a screw and a machine is quite inadequate to show the interdependence of mind and body, because the screw does cause the machine to work, but the machine does not cause the screw to work; so that their relation is not interdependence. On the contrary, body causes mind to work, and at the same time mind causes body to work; so that their relation is perfectly interdependent, and the relation is not that of an addition of mind to body, or of body to mind, as the screw is added to the machine. Bergson must have compared the working of the machine with mind, and the machine itself with body, if be wanted to show the real fact.