320 NATURAL THEOLOGY. 



But admit the sparrow by some means to know 

 that within that egg was concealed the principle 

 of a fliture bird : from what chemist was she to 

 learn that warmth was necessary to bring it to 

 maturity, or that the degree of warmth imparted 

 by the temperature of her own body was the de- 

 gree required ? 



To suppose, therefore, that the female bird acts 

 in this process from a sagacity and reason of her 

 own, is to suppose her to arrive at conclusions 

 which there are no premises to justify. If our 

 sparrow, sitting upon her eggs, expect young spar- 

 rows to come out of them, she forms, I will ven- 

 ture to say, a wild and extravagant expectation, 

 in opposition to present appearances and to pro- 

 bability. She must have penetrated into the order 

 of nature further than any faculties of ours will 

 carry us ; and it hath been well observed, that this 

 deep sagacity, if it be sagacity, subsists in conjunc- 

 tion wath great stupidity, even in relation to the 

 same subject. " A chemical operation," says Ad- 



are inclined, so M. Reaumur found that all chickens chip the 

 shell in the same direction, from left to right ; and that the circle 

 in which they chip, invariably cuts the egg at right angles to its 

 transverse axis, and not obliquely. The instrument wliich the 

 chicken employs is a small protuberance on its upper mandible, 

 called the bill-scale, which has no other use,. and accordingly drops 

 off soon after the bird is hatched. If any one should consider this 

 as a different operation in kind from those usually ascribed to in- 

 stinct in animals that are formed, a little reflection will probably 

 show him the impossibility of drawing any such line of distinction. 

 See the Dissertation on Instinct, Appendix. 



