596 LETTERS. 



by the veins back to the heart, and with such an ebb and flow, 

 in such mass and quantity that it must necessarily move 

 in some way in a circuit. But if you will be kind enough to 

 refer to my eighth and ninth chapters you will find it stated 

 in so many words that I have purposely omitted to speak of 

 the concoction of the blood, and of the causes of this motion 

 and circulation, especially of the final cause. So much I 

 have been anxious to say, that I might purge myself in the 

 eyes of a learned and much respected man, that I might feel 

 absolved of the infamy of meriting such censure. And I beg 

 you to observe, my learned, my impartial friend, if you would 

 see with your own eyes the things I affirm in respect of the 

 circulation, and this is the course which most beseems an 

 anatomist, that I engage to comply with your wishes, when- 

 ever a fit opportunity is afforded ; but if you either decline 

 this, or care not by dissection to investigate the subject for 

 yourself, let me beseech you, I say, not to vilipend the in- 

 dustry of others, nor charge it to them as a crime; do not 

 derogate from the faith of an honest man, not altogether foolish 

 nor insane, who has had experience in such matters for a long 

 series of years. 



Farewell, and beware ! and act by me, as I have done by 

 you ; for what you have written I receive as uttered in all 

 candour and kindness. Be sure, in writing to me in return, 

 that you are animated by the same sentiments. 

 Nurnberg, May 20th, 1636. 



LETTER II. 



To Paul Marquard Slegel, of Hamburg. 



I congratulate you much, most learned sir, on your excellent 

 commentary, in which you have replied in a very admirable 

 manner to Biolanus, the distinguished anatomist, and, as you 

 say, formerly your teacher : invincible truth has, indeed, taught 

 the scholar to vanquish the master. I was myself preparing 

 a sponge for his most recent arguments ; but intent upon 

 my work ' On the Generation of Animals' (which, but just 



