I THE DARWINIAN HYPOTFTESIS 21 



brought to the test of observation and experiment. 

 The path he bids us follow professes t o be, not a 

 mere airy track, fabricated of ideal cobwebs, but a 

 solid and broad bridge of facts. If it be so, it 

 will carry us safely over many a chasm in our 

 knowledge, and lead us to a region free from the 

 snares of those fascinating but barren virgins, the 

 Final Causes, against whom a high authority has so 

 justly warned us. " My sons, dig in the vineyard/' 

 were the last words of the old man in the fable : 

 and, though the sons found no treasure, they made 

 their fortunes by the grapes. 



