INTRODUCTION. li 



how anything can possibly go right unless he sees to 

 it himself. Nature works departmentally and by way 

 of leaving details to subordinates. But though those 

 who see nature thus do indeed deny design of the pre- 

 scient-from-all-eternity order, they in no way impugn 

 a method which is far more in accord with all that we 

 commonly think of as design. A design which is as 

 incredible as that a ewe should give birth to a lion 

 becomes of a piece with all that we observe most 

 frequently if it be regarded rather as an aggregation 

 of many small steps than as a single large one. This 

 principle is very simple, but it seems difBcult to under- 

 stand. It has taken several generations before people 

 would admit it as regards organism even after it was 

 pointed out to them, and those who saw it as regards 

 organism still failed to understand it as regards design ; 

 an inexorable " Thus far shalt thou go and no farther " 

 barred them from fruition of the harvest they should 

 have been the first to reap. The very men who most 

 insisted that specific difierence was the accumulation of 

 differences so minute as to be often hardly, if at all, 

 perceptible, could not see that the striking and baffling 

 phenomena of design in connection with organism 

 admitted of exactly the same solution as the riddle 

 of organic development, and should be seen not as 

 a result reached per saltum, but as an accumulation 

 of small steps or leaps in a given direction. It was 

 as though those who had insisted on the derivation of 

 all forms of the steam-engine from the common kettle, 

 and who saw that this stands in much the same rela- 

 tions to the engines, we will say, of the Great Eastern 



