380 ON GENERATION. 



tardation, in turbulence and strength, or debility, it is manifest 

 that the blood perceives things that tend to injure by irritating, 

 or to benefit by cherishing it. We therefore conclude that 

 the blood lives of itself, and supplies its own nourishment ; and 

 that it depends in nowise upon any other part of the body, 

 which is either prior to itself or of greater excellence and worth. 

 On the contrary, the whole body, as posthumous to it, as added 

 and appended as it were to it, depends on the blood, though 

 this is not the place to prove the fact ; I shall only say, with 

 Aristotle, l that ' ' The nature of the blood is the undoubted 

 cause wherefore many things happen among animals, both as 

 regards their tempers and their capacities " To the blood, 

 therefore, we may refer as the cause not only of life in general, 

 inasmuch as there is no other inherent or influxive heat that 

 may be the immediate instrument of the living principle except 

 the blood, but also of longer or shorter life, of sleep and 

 watching, of genius or aptitude, strength, &c. " For through 

 its tenuity and purity," says Aristotle in the same place, " ani- 

 mals are made wiser and have more noble senses ; and in like 

 manner they are more timid and courageous, or passionate and 

 furious, as their blood is more dilute, or replete with dense 

 fibres." 



Nor is the blood the author of life only, but, according to 

 its diversities, the cause of health and disease likewise : so that 

 poisons, which come from without, such as poisoned wounds, 

 unless they infect the blood, occasion no mischief. Life and 

 death, therefore, flow for us from the same spring. " If the 

 blood becomes too diffluent," says Aristotle, 2 "we fall sick; 

 for it sometimes resolves itself into such a sanguinolent serum, 

 that the body is covered with a bloody sweat ; and if there be 

 too great a loss of blood, life is gone." And, indeed, not only 

 do the parts of the body at all times become torpid when blood 

 is lost, but if the loss be excessive, the animal necessarily dies. 

 I do not think it requisite to quote any particular experiment 

 in confirmation of these views : the whole subject would require 

 to be treated specially. 



The admirable circulation of the blood originally discovered 

 by me, I have lived to see admitted by almost all ; nor has 



1 De Part. Anim. lib. ii, cap. 4. a Hist. Anim. lib. iii, cap. 19. 



