vi TRANSLATOR'S INTRODUCTION. 



Willis was not_, however, solitary in his doctrine as to the 

 existence of two souls in man ;^ Gassendus, and Dr. Hammond, 

 a learned English divine (both his contemporaries), are specially- 

 quoted by him ; nor was he alone in his direct application of 

 natural science to mental philosophy, for Sylvius was diligently 

 pursuing at Leyden the same course of research which he was 

 following at Oxford. Sylvius, however, followed Descartes, 

 while Willis was influenced in the formation of his theories by 

 the doctrines of Paracelsus. There was, however, yet another 

 neuro-psychologist, whose name is less known in England, but 

 who was the contemporary of Sylvius and WilUs, and taught 

 identical or analogous doctrines, with brilliant success, at Jena, 

 — this was G. W. Wedel, the teacher of Hoffmann and Stahl, 

 — and it is through him that we have to trace the views of 

 Unzer in a direct line from Willis. 



Hoffmann and Stahl ran a singularly parallel course through 

 life. They were born in the same year (1660), and studied at 

 the same time and place, under Wedel, at Jena, then the 

 most renowned university in Germany. They were appointed 

 professors of medicine at Halle, in the same year (1694), and 

 at the same age ; and both became physicians to the king of 

 Prussia ; Hoffmann was the first to leave HaUe, and fill that 

 office, but, in three years, he abandoned court, and resumed 

 his professor's chair, where he died, in the 83d year of his 

 age. Stahl died at Berlin, the physician to royalty; but, 

 previously to his removal from Halle, he was a professor 

 for twenty -two years. In the neuro-metaphysical doctrines 

 of both these great men, the influence of WiUis's views may 

 be traced, but the purely metaphysical bias of StahFs mind 

 soon showed itself; for he repudiated all histological, ana- 

 tomical, and bio-chemical researches, as worse than useless 

 in medicine. The foundation of his theory was wholly meta- 

 physical; the organism, considered as matter, had no power 

 to originate movement ; it could only be put into motion by 

 an immaterial principle, — the soul; and the laws of action 



individuum, quamdiu possit, sese tueatur: hsec divinae providentise lex est, creaturis 

 omnibus indita, quae vinculi instar vitae priiicipia alioqui dissipari, et ab invicem 

 discedere apta, una coUigat, et cui tanquam basi totius mundi duratio innititur," &c. 

 De Anima. Brutorum, Pars Physiolog. cap. vi. 



' Prochaska gives an account of Willis's views on this and other points, in his 

 * Dissertation on the Functions of the Nervous System,' chap, i, § vi. 



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