178 THE LAW. 



progress of research, by leading either to presumptuous 

 dogmatism on the one hand, or to ungenerous illiber- 

 ality on the other. They are submitted in the spirit of 

 honest earnestness, more anxious to arrive at the expression 

 of one plain truth than give currency to a thousand hypo- 

 theses, however brilliant and attractive. And yet, while 

 the main value must ever be ascribed to inductive reason- 

 ing from facts, hypothetical promptings cannot always be 

 ignored. They have their own value, and oftener than 

 once has the road to truth been indicated by the finger- 

 posts of hypothesis. 



[Dawn of Life.] 



As at present, so during all former life-epochs, the land 

 and waters were tenanted by various families of plants and 

 animals these families exhibiting affinities and gradations 

 even as plants and animals do now. It is true, that as we 

 descend into the rocky crust we arrive at a stage (the meta- 

 m orphic strata) when plants and animals do not seem to 

 have existed ; but on this point the evidence is merely 

 negative, and Geology cannot say with certainty that Life 

 was not coeval with the globe itself, though the presump- 

 tion is, that organic being was not called into existence 

 till about the dawn of the Silurian era. Nothing is gained 

 by the assumption that it had a prior existence, and that 

 every organism has been obliterated by the metamorphism 

 to which the earlier strata have been subjected. We can 

 only reason from what we know ; and in the mean time 

 the lowest Silurian or Cambrian rocks stand as the farthest 

 verge to which Palaeontology has pushed her discoveries. 



It has been argued, no doubt, that as the vertebrate ani- 

 mals seem to show an ascent through the geological periods 

 from fish to reptile, from reptile to bird, and from bird to 

 mammal, so the invertebrate may also obey a similar law of 



