Different conditions and the changes that take place in the world have their effect upon the mind, and the different conditions of the mind have their effect upon the body. As bodily illness makes man irritable, confused and exhausted in mind, so different conditions of the mind cause health or illness in the body. The link between the body and the mind is the breath, a link through which the influences of the body and the mind are exchanged and work upon one another. By the use of breath in physical culture the health and vigor of the breath is projected, so to speak, upon the mind. By the use of concentration through the breath the light of the mind is thrown upon the body, which takes away from the body all heaviness and stiffness, making it light and exhilarated.