NATURAL SELECTION AND ENVIRONMENT 173 



cular systems tlirougli mere material. But how can 

 personality in environment act on personality in man 

 except by personal contact or by symbols easy of 

 comprehension according to its own laws? Some 

 method of attaining acquaintance at least we should 

 certainly expect. 



But some of you may ask, How can any theory of 

 evolution guarantee that anything of the present shall 

 survive in the future ? It is continually changing and 

 destroying former types. The old order of everything 

 changes and passes away, giving place to the new. 

 But is this the whole truth ? Evolution is a radical 

 process, but we must never forget that it is also, and 

 at the same time, exceedingly conservative. The cell 

 was the first invention of the animal kingdom, and all 

 higher animals are and must be cellular in structure. 

 Our tissues were formed ages on ages ago ; they have 

 all persisted. Most of our organs are as old as worms. 

 All these are very old, older than the mountains, and 

 yet I cannot doubt that they must last as long as man 

 exists. Indeed, while Nature is wonderfully inventive 

 of new structures, her conservatism in holding on to 

 old ones is still more remarkable. In the ascending 

 line of development she tries an experiment once ex- 

 ceedingly thorough, and then the question is solved 

 for all time. For she always takes time enough to try 

 the experiment exhaustively. It took ages to find how 

 to build a spinal column or brain, but when the ex- 

 periment was finished she had reason to be, and was, 

 satisfied. And if this is true of bodily organs we 

 should expect that the same law would hold good 

 when the animal development gradually passes over 

 into the spiritual. And what is human history but 



