14 SCIENCE FROM AN EASY CHAIR 



properties of natural things, which we know as the laws of 

 physics and chemistry. Most important and dominating 

 of all these results is the inevitable one that man himself 

 has come from animal ancestors, in the same way, and 

 (this is the greatest and most far-reaching conclusion of 

 all) that he is still subject to those natural processes of 

 change and development by which he has reached his 

 present phase ; that he must completely understand them 

 and control them (so far as such control is possible) in 

 order to maintain a healthy, happy, and improving race of 

 men on the face of the globe. This great possession the 

 earth and all that lives on it is, as Lord Bacon phrased it 

 three hundred years ago the Kingdom of Man. Man has 

 but to use his intelligence in order to take control of it. 

 The knowledge of his own relation to it, and of the ways 

 in which the human race is affected for good and for ill, 

 through the operation of the self-same processes which 

 affect the breeding, the improvement, the health, the 

 disease, the destruction, and the perfecting of other living 

 things, has once and for all been placed within man's 

 reach by the discoveries of Darwin and Wallace. 



Before Darwin that is, before 1st July 1858 the origin 

 of the different species of animals and plants was called 

 by great thinkers like Sir John Herschel, the astronomer, 

 " the mystery of mysteries." The word " species " was 

 denned as " an animal or plant which in a state of nature 

 is distinguished by certain peculiarities of form, size, 

 colour, or other circumstance from any other animal or 

 plant, and propagates after its kind individuals perfectly 

 resembling the parent, its peculiarities being therefore 

 permanent." So wrote a great naturalist in the days 

 before Darwin. This definition may be illustrated by 

 two common English birds the rook and the crow. 

 They differ from each other in slight peculiarities of 

 form, structure, and habits, and, moreover, rooks always 



