AND CELLULAR PSYCHOLOGY. 53 



prejudices of the dualistic doctrine, and for my con- 

 version to the monistic, as to Eudolf Virchow ; for it 

 was his superior guidance which most firmly con- 

 vinced me, and many others, of the exclusive import- 

 ance of the mechanical view of nature. He led me 

 to a clear recognition of the fact that the nature of 

 man, like every other organism, can only be rightly 

 understood as a united whole, that this spiritual and 

 corporeal being are inseparable, and that the pheno- 

 mena of the soul-life depend, like all other vital 

 phenomena, on material motion only on mechanical 

 (or physico-chemical) modifications of cells. And it 

 was in perfect agreement with my most honoured master 

 that I subscribed then, and at this day still subscribe, 

 to the proposition with which he, in September 1849, 

 closed the preface to the above-mentioned " Efforts at 

 Unity." " It is possible that I may have erred in 

 details ; in the future I shall be ready and willing to 

 acknowledge my mistakes and to rectify them, but 

 I enjoy this conviction, that I shall never find myself 

 in the position of denying the principle of the unity of 

 the human nature with all its consequences ! " 



To err is human ! Who can say to what diametrical 

 contradiction to his firmest convictions man may not in 

 the future be driven by his adaptation to new relations in 

 life ? If we compare these stout monistic declarations 

 of 1849 and 1858 with the equally decided dualistic 



