FROM KNOWN TO UNKNOWN 5 



and over it an imposing record of many a Mann, and yet further 

 he may go, and from the Heralds' College find out the still earlier 

 derivation of his ancestors. 



Detection of a Crime. 



There are two chief ways of detecting a crime. By oral evidence 

 from eye-witnesses or confession of the accused you may get direct 

 proof, though even here are pitfalls from careless and hasty witnesses 

 on the one hand, or on the other from a strange perversion of mind 

 of the confessing person which is well enough known to forensic 

 medicine. You may thus bring home to the accused his guilt by 

 the method of the annalist. Or you may employ the more common 

 method of studying circumstantial evidence ; the story of the crime 

 is read backwards and a verdict of guilty is given. This is the 

 main stuff of which the prevalent detective story is composed. 



A Parable. 



A plain parable may well conclude this chapter. 



As I mused on the chain of life I found a piece of whipcord 

 which had been lying by for twenty-five years since some of it was 

 used for rigging a model yacht, and this very efficient product of 

 human art seemed to speak to me on the subject of my musings. 

 Perhaps if Huxley could extract from a piece of chalk or lumps of 

 coal two magnificent expositions on geology and biology, this little 

 trifle of cord might afford a text on a way of looking at living things 

 which should be useful in this old case of Lamarck v. Weismann — 

 and others. 



Should I learn the story of the whipcord forwards like an annal- 

 ist, or backward like a modern historian ? Clearly it could be done 

 in a measure by either method. Here was a highly finished product 

 of which either might furnish the story, and of which, we may suppose, 

 I knew nothing. I tried the backward way, and by the aid of a 

 needle began to unravel it. The cord was as good as if just made, 

 slender, strong, twisted, with some glazing on the twisted threads. 

 It showed three main bundles, and each of these was composed of 

 two smaller ones. The substance of all these six was found when 

 examined with a lens to consist of minute silky fibres varying 

 from a quarter of an inch to an inch in length. This was all I could 

 learn without a stronger magnifying power or a chemical analysis, 

 and the direct search was at an end. I gathered since then that 

 the first three bundles were called " strands," and the two composing 

 each of these " yarns," and that the fibres were from a plant called 

 hemp. This did not carry the story deep or far, and illustrates 



