LIFE ON THE EARTH, 205 



which were accepted for deity by the ' too superstitious' 

 men of Athens and Rome. Erroneous opinions have 

 but their day, and are, perhaps, less mischievous than 

 the indolence which acquiesces in dull and incurious 

 conformity with whatever may reign for the moment. 

 Truth, or what appears such to human reason, ope- 

 rating on real facts and just inferences, this is the 

 end of scientific research ; while we seek it, let us 

 not be too much troubled if some run in courses 

 wide of our own, and ask questions we think not 

 likely to be answered. If we do not ourselves believe 

 the origin of created life to be discoverable by a 

 creature limited to the observation of sensible phe- 

 nomena, why should we restrain the enterprise of 

 those who, vainly striving after something that is 

 unattainable or fabulous, may yet win much that is 

 accessible, valuable and real? 



According to most of the hypotheses we have 

 been considering, the forms, structures and habits 

 of life, which we now circumscribe by specific cha- 

 racters, however distinct these may seem to be, are 

 only constant for this moment, slowly varying through 

 this period, as they have varied in preceding periods, 

 possibly then at 'a greater rate than now. The forms 

 that now are have had a long series of progenitors, 

 gradually changing from the earliest times ; many of 

 the earlier races of a great common stock having 



