II OF THE NATURAL HISTORY SCIENCES 57 



But I shall be asked at once, Do you mean to 

 say that there is no difference between the habit 

 of mind of a mathematician and that of a natural- 

 ist ? Do you imagine that Laplace might have 

 been put into the Jardin des Plantes, and Cuvier 

 into the Observatory, with equal advantage to the 

 progress of the sciences they professed ? 



To which I would reply, that nothing could be 

 further from my thoughts. But different habits 

 and various special tendencies of two sciences do 

 not imply different methods. The mountaineer 

 and the man of the plains have very different 

 habits of progression, and each would be at a loss 

 in the other's place ; but the method of progression, 

 by putting one leg before the other, is the same in 

 each case. Every step of each is a combination of 

 a lift and a push ; but the mountaineer lifts more 

 and the lowlander pushes more. And I think the 

 case of two sciences resembles this. 



I do not question for a moment, that while the 

 Mathematician is busy with deductions from 

 general propositions, the Biologist is more es- 

 pecially occupied with observation, comparison, 

 and those processes which lead to general proposi- 

 tions. All I wish to insist upon is, that this 

 difference depends not on any fundamental dis- 

 tinction in the sciences themselves, but on the 

 accidents of their subject-matter, of their relative 

 complexity, and consequent relative perfection. 



The Mathematician deals with two properties of 



