DISCOURSE ON METHOD. 51 



which, taking its rise in the heart, is divided, after 

 passing out from it, into many branches which pres- 

 ently disperse themselves all over the lungs ; in the 

 second place, the cavity in the left side, with which 

 correspond in the same manner two canals in size 

 equal to or larger than the preceding, viz., the 

 venous artery, (arteria venosa,} likewise inappro- 

 priately thus designated, because it is simply a vein 

 which comes from the lungs, where it is divided into 

 many branches, interlaced with those of the arterial 

 vein, and those of the tube called the windpipe, 

 through which the air we breathe enters; and the 

 great artery which, issuing from the heart, sends its 

 branches all over the body. I should wish also that 

 such persons were carefully shewn the eleven 

 pellicles which, like so many small valves, open and 

 shut the four orifices that are in these two cavities, 

 viz., three at the entrance of the hollow vein, where 

 they are disposed in such a manner as by no means 

 to prevent the blood which it contains from flowing 

 into the right ventricle of the heart, and yet exactly 

 to prevent its flowing out ; three at the entrance to 

 the arterial vein, which, arranged in a manner 

 exactly the opposite of the former, readily permit 

 the blood contained in this cavity to pass into the 

 lungs, but hinder that contained in the lungs from 

 returning to this cavity; and, in like manner, two 

 others at the mouth of the venous artery, which 

 allow the blood from the lungs to flow into the left 

 cavity of the heart, but preclude its return; and 

 three at the mouth of the great artery, which suffer 

 the blood to flow from the heart, but prevent its 



