DIFFERENTIATION AND REJUVENATION 155 



before you the thoughts which have been accumulated 

 as the result of the studies of many years. It is a result 

 of differentiation that you have such parts that you not 

 only hear the actual sound of my voice, but interpret 

 at least I hope so the meaning of my words and can 

 understand the ideas which I am endeavouring to pre- 

 sent to you. If you carry away something from these 

 lectures, and recall it at some future time, that also 

 will be a result of the differentiation of structure ; for 

 every one of you started as a minute germ, consisting 

 of protoplasm with a nucleus, and entirely without 

 any differentiation ; and by a process so intricate that 

 the mystery of it escapes entirely all our powers of 

 analysis, those parts which you have have been slowly 

 and secretly fashioned. We have approached one of the 

 fundamental problems of existence. When we talk of 

 dfferentiation, we talk of the endowments which bring 

 us into relation with the external world -into rela- 

 tions with our kind, and which make our internal life 

 so complex, a complexity which in itself is a great 

 problem. We touch here the fundamental mysteries 

 of existence ; we are hovering upon the outskirts of 

 our human conceptions. We are not yet able to press 

 beyond. But perhaps the time may come when the 

 limit to which I can now bring you will be moved 

 farther back, and some of the things which are at the 

 present time utterly mysterious and incomprehensible 

 to us will be comprehended and be explicable to you. 

 The increase of the protoplasm is then, as we have 

 clearly seen from the pictures, the mark both of 



