If the excretions do not cause death immediately, but settle round the lungs and windpipe for they collect first in the upper part of the body, because we are warmed by the air, for it is owing to this that ophthalmia occurs before fever in an unhealthy summer if then, as I have said, the excretions in the upper parts of the body do not immediately kill the patient, they descend in an unconcocted condition into the stomach; and thus dysentery is caused, because the moisture owing to its abundance is not discharged.