STUDIES IN ANIMAL LIFE. 143 



" Your reflections on the differences between ani- 

 mals and plants," lie writes, "in the passage to 

 which I previously referred, will be the more agree- 

 able to me, because I am at present working out a 

 new plan of a general natural history. I think we 

 ought carefully to seek out the relation of all exist- 

 ences with the rest of nature, and, above all, to show 

 their part in the economy of the great All. In this 

 work I should desire that the investigator should 

 start from the simplest things, such as air and wa- 

 ter, and after having spoken of their influence on 

 the whole, he should pass gradually to the com- 

 pound minerals, from these to plants, and so on; 

 and that at each stage he should ascertain the exact 

 degree of composition, or, which is the same thing, 

 the number of properties it presents over and above 

 those of the preceding stage, the necessary effects 

 of these properties, and their usefulness in creation. 

 Such a work is yet to be executed. The two works 

 of Aristotle, De Historia Animdlium, and De Parti- 

 bus Animalium, which I admire more each time that 

 I read them, contain a part of what I desire, name- 

 ly, the comparison of species, and many of the gen- 

 eral results. It is, indeed, the first scientific essay 

 at a natural history. For this reason it is necessa- 

 rily incomplete, contains many inaccuracies, and is 

 too far removed from a knowledge of physical laws." 

 He passes on from Aristotle to Pliny, Theophrastus, 

 Dioscorides, Aldovrandus, Gresner, Graspar Bauhin, 



