Book 4
22
EMPEDOCLES thinks, that the first breath the first animal drew was when the moisture in unborn infants was separated, and by that means an entrance was given to the external air into the gaping vessels, the moisture in them being evacuated. After this the natural heat, in a violent force pressing upon the external air for a passage, begets an expiration; but this heat returning to the inward parts, and the air giving way to it, causeth an inspiration. The respiration that now is arises when the blood is carried to the exterior surface, and by this fluxion drives the airy substance through the nostrils; thus in its recess it causeth expiration, but the air being again forced into those places which are emptied of blood, it causeth an inspiration. To evince which, he proposeth the instance of a water-clock, which gives the account of time by the running of water.
