The spirit produces this physical body out of itself, so the body, in spite of all the physical nourishment, entirely depends upon the spirit to live. One can live for some time without food and water, but one cannot live without breathing. The reason is that as the physical body is made of the spirit, it needs to breathe spirit in, in order to exist. Breath, therefore, does not only nourish the physical body, but it gives subsistence to all the planes of man's existence.