Diseases of the body arise (i) when any of the four elements is out of place or there is too much or too little of them in any part: and (ii) when blood, flesh, and sinews are produced in a wrong order. The proper order is that flesh and sinew should be formed from blood, flesh from the liquid and sinew from the fibrous part of it; and that from these should exude a glutinous matter which nourishes bone and marrow. When this order is reversed, all sorts of bile and phlegm are generated. The various kinds of bile. Of phlegm there is an acid and a white sort. Stages of the disease:—(1) When the flesh is attacked, if the foundations remain sound, there is less danger. (2) There is more when the flesh falls away from the sinews and bones. (3) Worse still are the prior disorders, such as crumbling away and gangrene of the bones; and (4) worst of all is disease of the spinal marrow.] Now every one can see whence diseases arise.