To The Moft Illuftrious and Indomitable 

 Trince CHARLES, KING o/ GRE.fT BRIT- 



yflN, FRANCE and IREI^ND, DEFENDER of 

 the VAim 



Most Illustrious Prince! 

 The heart of animals is the foundation of their life, the 

 sovereign of everything within them, the sun of their micro- 

 cosm, that upon which all growth depends, from which all 

 power proceeds. The King, in like manner, is the foundation 

 of his kingdom, the sun of the world around him, the heart of the 

 republic, the fountain whence all power, all grace doth flow. 

 What I have here written of the motions of the heart I am the 

 more emboldened to present to your Majesty, according to the 

 custom of the present age, because almost all things human are 

 done after human examples, and many things in a King are 

 after the pattern of the heart. The knowledge of his heart, 

 therefore, will not be useless to a Prince, as embracing a kind 

 of Divine example of his functions, — and it has still been usual 

 with men to compare small things with great. Here, at all 

 events, best of Princes, placed as you are on the pinnacle of 

 human affairs, you may at once contemplate the prime mover 

 in the body of man, and the emblem of your own sovereign 

 power. Accept, therefore, with your wonted clemency, I most 

 humbly beseech you, illustrious Prince, this, my new Treatise 

 on the Heart; you, who are yourself the new light of this age, 

 and, indeed, its very heart; a Prince abounding in virtue and in 

 grace, and to whom we gladly refer all the blessings which 

 England enjoys, all the pleasure we have in our lives. 



Your Majesty's most devoted servant, 

 William Harvey 

 (London .... 1628.) 



(Translation by Robert Willis, M.D., 1847,) 

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