252 EXPERIMENTAL EVOLUTION LECT. 



allies which provide him with meat, milk, wool, or 

 energy. But, since man has been able to do what he 

 has done, while devoid of knowledge and unconscious 

 of methods, what may he not expect to perform now, 

 with larger means, more varied resources, many 

 centuries of accumulated science, and the certainty of 

 success if he is persevering enough ? The past is a 

 promise for the future, and the results already obtained 

 well show what we may attain to ; the whole thing 

 rests in our hands. Are we to believe that among 

 the unnumbered species of animals and plants which 

 are yet living in the wild state, none remain which may 

 be cultivated or domesticated ? Has all been done that 

 was possible ? No naturalist would venture to answer 

 yes, and to say that man has reached his Pillars of 

 Hercules. We are then entitled to expect many 

 useful discoveries if we only set to work, and the field 

 which lies open to us is infinite. Both organic king- 

 doms may be made to yield any number of new forms 

 whose use we cannot even foresee, so short-sighted 

 are we ; and even if we were only to increase the 

 number of the useful animals or plants, without varying 

 the use to which either may be put, a great deal would 

 doubtless have been done for the benefit of mankind. 



But this cannot happen if we do not purposely set 

 to work. In former times, when man lived in small 

 or large tribes, widely separated, without easy means 



