CHAPTER V. 



THE ARGUMENTS FROM EMBRYOLOGY. 



§ 127a. Already I have emphasized the truth that Nature 

 is always more complex than we suppose (§ 74a) — that there 

 are complexities within complexities. Here we find illus- 

 trated this truth under another aspect. When seeking to 

 formulate the arguments from Embryology, we are shown 

 that the facts as presented in Nature are not to be expressed 

 in the simple generalizations we at first make. 



While w^e recognize this truth we must also recognize the 

 truth that only by enunciation and acceptance of imperfect 

 generalizations can we progress to perfect ones. The order 

 of Evolution is conformed to by ideas as by other things. The 

 advance is, and must be, from the indefinite to jhe definite. 

 It is impossible to express the totality of any natural pheno- 

 menon in a single proposition. To the primary statement 

 expressing that which is most dominant have to be added 

 secondary statements qualifying it. We see this even in so 

 simple a case as the flight of a projectile. The young artillery 

 officer is first taught that a cannon-shot describes a curve 

 treated as a parabola, though literally part of an extremely 

 eccentric ellipse not distinguishable from a parabola. Pre- 

 sently he learns that atmospheric resistance, causing a con- 

 tinual decrease of velocity, entails a deviation from that 

 theoretical path which is calculated on the supposition that 

 the velocity is uniform; and this incorrectness he has to 

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