570 UNITY OF DESIGN. 



between fishes and warm-blooded quadrupeds ; for 

 these are but detached links of a broken chain, 

 tending, indeed, to prove the unity of the designs 

 of Nature, but showing also the specific character 

 of each of her creative efforts. The pursuit of 

 remote and often fanciful analogies has, by many 

 of the continental physiologists, been carried to an 

 unwarrantable and extravagant length ; for the 

 scope which is given to the imagination in these 

 seductive speculations, by leading us far away 

 from the path of philosophical induction, tends 

 rather to obstruct than to advance the progress of 

 real knowledge. By confining our inquiries to 

 more legitimate objects, we shall avoid the delusion 

 into which one of the disciples of this transcen- 

 dental school appears to have fallen, when he 

 announces, with exultation, that the simple laws 

 he has discovered have now explained the uni- 

 verse;* nor shall we be disposed to lend a patient 

 ear to the more presumptuous reveries of another 

 system-builder, who, by assuming that there exists 

 in organized matter an inherent tendency to per- 

 fectibility, fancies that he can supersede the opera- 

 tions of Divine agency. t 



Very diff'erent was the humble spirit of the great 

 Newton, who, struck with the immensity of nature, 



* '• L'univers est explique, et nous le voyons ; c'est un petit 

 nombre de principes generaux et feconds qui nous en ont donne la 

 clef." Serres, Ann. des Sc. Nat, xi. 50. 



t Allusion is here made to the celebrated theory of Lamarck, as 

 exposed in his " Philosophic Zoologique." He conceives that there 

 was originally no distinction of species, but that each race has, in the 

 course of ages, been derived from some other, less perfect than itself, 

 bv a spontaneous effort at improvement; and he supposes that 

 infusorial animalcules, spontaneously formed out of organic molecules. 



