CIRCULATION, 



147 



Such is the description, and with the exception of the first proof, 

 such the evidence of the circulation of the blood in the human 

 body, pretty much as it was given by the discoverer of it, the illus- 

 trious Harvey. Before the time of Harvey, a vague and indistinct 

 conception that the blood was not without motion in the body had 

 been formed by several anatomists. It is analogous to the ordinary 

 mode in which the human mind arrives at discovery, that many 

 minds should have an imperfect perception of an unknown truth, 

 before some one mind sees it in its completeness and fully discloses 

 it. Having, about the year 1629, succeeded in completely tracing 

 the circle in which the blood moves, and having at that time col- 

 lected all the evidence of the fact, with a rare degree of philosophi- 

 cal forbearance, Harvey still spent no less than eight years in re- 

 examining the subject, and in maturing the proof of every point, 

 before he ventured to speak of it in public. The brief tract which 

 at length he published was written with extreme simplicity, clear- 

 ness, and perspicuity, and has been justly characterized as one of 

 the most admirable examples of a series of arguments deduced from 

 observation and experiment that ever appeared on any subject. 



Contemporaries are seldom grateful to discoverers. More than 

 one instance is on record in which a man has injured his fortune 

 and lost his happiness through the elucidation and establishment of 

 a truth which has given him immortality. It may be that there are 

 physical truths yet to be brought to life, to say nothing of new 

 applications of old truths, which, if they could be announced and 

 demonstrated to-day, would be the ruin of the discoverer. It is 

 certain that there are moral truths to be discovered, expounded, and 

 enforced, which, if any man had now penetration enough to see 

 them, and courage enough to express them, would cause him to be 

 regarded by the present generation with horror and detestation. 

 Perhaps, during those eight years of re-examination, the discoverer 



