ON GENERATION. 207 



parts in diversity of the matter whence they arise. Thus me- 

 dical men assert that the several parts of the body are both 

 engendered and nourished by diverse matters, either the blood 

 or the seminal fluid; viz. the softer parts, such as the flesh, 

 by the thinner matter, the harder and more earthy parts, 

 such as the "bones, &c. by the firmer and thicker matter. 

 But we have elsewhere refuted this too prevalent error. Nor 

 do they err less who, with Democritus, compose all things of 

 atoms; or with Empedocles, of elements. As if generation were 

 nothing more than a separation, or aggregation, or disposition 

 of things. It is not indeed to be denied, that when one thing 

 is to be produced from another, all these are necessary, but 

 generation itself is different from them all. I find Aristotle to 

 be of this opinion; and it is my intention, by-and-by, to teach 

 that out of the same albumen (which all allow to be uniform, 

 not composed of diverse parts,) all the parts of the chick, bones, 

 nails, feathers, flesh, &c. are produced and nourished. More- 

 over, they who philosophize in this way, assign a material cause 

 [for generation], and deduce the causes of natural things either 

 from the elements concurring spontaneously or accidentally, or 

 from atoms variously arranged; they do not attain to that which 

 is first in the operations of nature and in the generation and 

 nutrition of animals ; viz. they do not recognize that efficient 

 cause and divinity of nature which works at all times with con- 

 summate art, and providence, and wisdom, and ever for a certain 

 purpose, and to some good end; they derogate from the honour 

 of the Divine Architect, who has not contrived the shell for the 

 defence of the egg with less of skill and of foresight than he has 

 composed all the other parts of the egg of the same matter, and 

 produced it under the influence of the same formative faculty. 



Although what has already been said be the fact, namely, 

 that the egg, even whilst contained in the uterus, is provided 

 with a hard shell, still the authority of Aristotle has always 

 such weight with me that I never think of differing from him 

 inconsiderately; and I therefore believe, and my observations 

 bear me out in so much, that the shell does gain somewhat in 

 solidity from the ambient air upon its extrusion ; that the slug- 

 gish and slippery fluid with which it is moistened when laid, 

 immediately becomes hardened on its exposure to the air. For 

 the shell, whilst the egg is in the uterus, is much thinner and 



