METAMORPHOSIS OF TISSUES. 131 



derived from it in opposition to the views developed 

 in the preceding part of this work, with which it 

 has no manner of connection. The results here to 

 be described have surprised me no less than they 

 will others, and have excited in my mind the same 

 doubts as others will conceive ; but they are not the 

 creations of fancy, and I give them because I enter- 

 tain the deep conviction that the method which has 

 led to them is the only one by which we can hope 

 to acquire insight into the nature of the organic 

 processes. 



The numberless qualitative investigations of ani- 

 mal matters which are made are equally worthless 

 for physiology and for chemistry, so long as they are 

 not instituted with a well-defined object, or to answer 

 a question clearly put. 



If we take the letters of a sentence which we wish 

 to decipher, and place them in a line, we advance 

 not a step towards the discovery of their meaning. 

 To resolve an enigma, we must have a perfectly clear 

 conception of th^ problem. There are many ways 

 to the highest pinnacle of a mountain ; but those 

 only can hope to reach it who keep the summit 

 constantly in view. All our labour and all our 

 efforts, if we strive to attain it through a morass, 

 only serve to cover us more completely with mud ; 

 our progress is impeded by difficulties of our own 

 creation, and at last even the greatest strength 

 must give way when so absurdly wasted. 



21. If it be true that all parts of the body are 



K 2 



