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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 combi- 

 nation 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 Mathe- 

 matician is busied with deductions from general pro- 

 positions, the Biologist is more especially occupied with 

 observation, comparison, and those processes which lead 

 to general propositions. All I wish to insist upon is, 

 that this difference depends not. on any fundamental 

 distinction in the sciences themselves, but on the ac- 

 cidents of their subject-matter, of their relative com- 

 plexity, and consequent relative perfection. 



The Mathematician deals with two properties of 

 objects only, number and extension, and all the in- 

 ductions he wants have been formed and finished ages 

 ago. He is occupied now with nothing but deduction 

 and verification. 



The Biologist deals with a vast number of properties 

 of objects, and his inductions will not be completed, I 

 fear, for ages to come ; but when they are, his science 

 will be as deductive and as exact as the Mathematics 

 themselves. 



>6uch is the relation of Biology to those sciences which 

 deal with objects having fewer properties than itself. 

 But as the student, in reaching Biology, looks back upon 

 sciences of a less complex and therefore more perfect 

 nature ; so, on the other hand, does he look forward to 

 other more complex and less perfect branches of know- 

 ledge. Biology deals on]y with living beings as isolated 

 things treats only of the life of the individual : but 

 there is a higher division of science still, which considers 

 living beings as aggregates which deals with the rela- 



