28 DIFFERENT KINDS OF EVIDENCE. 



reasoners to assign to one class of evidence the cogency 

 which belongs to another, and perhaps to that alone. 

 History has one kind of evidence ; mathematics another ; 

 and you have often been shown in what consists its 

 peculiar value, and whence its appropriate force, its 

 indubitable certainty, flow. So again, another kind of 

 evidence belongs to natural philosophy ; while the phi- 

 losophy of human nature and of morals has another 

 quite distinct from all these. The subordinate branches 

 of the several parts have still minuter peculiarities in 

 the evidence appropriated to them. Now, an enlarged 

 and unprejudiced mind will, in each of these, yield his 

 conviction to that species of argument and that kind 

 and measure of evidence which manifestly accords with 

 the subject before him ; and no man can fairly claim the 

 title of a sound reasoner who employs or expects, with 

 regard to a historical fact, the evidence which he requires 

 in confirmation of a geometrical truth. You know very 

 well that testimony is not admitted in proof of any 

 mathematical proposition, because mathematical evi- 

 dence is of a totally different kind. Yet mathematicians 

 are not the only persons who exercise a rational belief. 

 In natural philosophy, a science in various respects 

 scarcely, if at all, inferior to pure mathematics in the 

 certainty of its conclusions, you receive testimony as an 

 ample proof of many facts. It is, therefore, agreeable 

 to reason and sound philosophy, to accredit cautiously 

 analyzed testimony. Besides which, it is demonstrable 

 on mathematical principles, that the concurrent testimony 

 of competent witnesses may, in numerous instances, 

 furnish evidence, which is really irresistible, of the most 

 extraordinary and improbable events. 



II. Nor, again, must you suffer yourselves to be seduced 



