THE UNITY OF NATURE. 277 



presumption, loves to call " the history of the world "? 

 Do we find in every phase of it a lofty moral principle 

 or a wise ruler, guiding the destinies of nations? 

 There can be but one answer in the present advanced 

 stage of natural and human history : No. The fate 

 of those branches of the human family, those nations 

 and races which have struggled for existence aud 

 progress for thousands of years, is determined by the 

 same "eternal laws of iron" as the history of the 

 whole organic world which has peopled the earth for 

 millions of years. 



Geologists distinguish three great epochs in the 

 organic history of the earth, as far as we can read it 

 in the monuments of the science of fossils — the 

 primary, secondary, and tertiary epochs. According 

 to a recent calculation, the first occupied at least 

 34,000,000, the second 11,000,000, and the third 

 3,000,000 years. The history of the family of verte- 

 brates, from which our own race has sprung, unfolds 

 clearly before our eyes during this long period. 

 Three different stages in the evolution of the verte- 

 brate correspond to the three epochs ; the fishes 

 characterised the primary (palaeozoic) age, the reptiles 

 the secondary (mesozoic), and the mammals the 

 tertiary (caenozoic). Of the three groups the fishes 

 rank lowest in organisation, the reptiles come next, 

 and the mammals take the highest place. We find, 

 on nearer examination of the history of the three 

 classes, that their various orders and families also 

 advanced progressively during the three epochs 

 towards a higher stage of perfection. May we con- 

 sider this progressive development as the outcome of 

 a conscious design or a moral order of the universe ? 

 Certainly not. The theory of selection teaches us 



