Heart and Blood 89 



compression of the muscles generally. The blood is 

 thus more disposed to move from the circumference to 

 the centre than in the opposite direction, were there 

 even no valves to oppose its motion ; whence that it may 

 leave its source and enter more confined and colder 

 channels, and flow against the direction to which it 

 spontaneously inclines, the blood requires both force 

 and an impelling power. Now such is the heart and 

 the heart alone, and that in the way and manner 

 already explained. 



