33 



mere succession indicates causation by its analogy to the order 

 in which we experience dependence: this analogy is to the syn- 

 thetical proof of dependence; but is often invalidated by the 

 analytical test: that is, the consequence which succeeds in a few 

 instances to a certain precursor, is found, upon further experience, 

 or a closer investigation, to be capable of existing without it. This 

 doctrine will be further enlarged upon in a future instance, where 

 the truth of its application is a matter of some importance. 



71. Although in the gross we contemplate an effect as a single 

 thing, yet its properties are infinite, or it includes within itself an 

 infinity of forms of existence. The causes of one part of an effect, by 

 pursuing an analysis, in possibility, justly supposed, are without num- 

 ber: and the relation of the causes causarum of one part, with those of 

 the other, produce individual effects which are also incalculable, and 

 serve to diversify to an astonishing extent the forms of existence. 

 The reason why we do not see all these things is, because only cer- 

 tain properties of things have a relation with our faculties; the 

 others of course have no influence upon them ; as an arm is to us 

 a sound arm, though it should be undergoing the preparatory 

 changes of an erysipelatous inflammation, which may shew itself in 

 two hours. Now the arm had digressed from health when we 

 thought it healthy ; but the relation of that act of causation was 

 not with our senses. The relation of the vesicles and the redness 

 is with our senses; and accordingly these phenomena are taken 

 account of by them. This is a clumsy example where the choice 

 lies among ten thousand. 



72. The chief end of investigation is to understand relations; 

 and these are the more complicated, the more extended the series 

 is which forms the subject of inquiry: but there are few men who 

 have the talent of combining, so as to comprehend in their view a 

 whole system of facts, or who are capable of connecting the parts of 

 an extensive chain; and fewer still who are adequate to the arduous 

 business of just analytical discrimination : and consequently, the rela- 

 tions even of familiar things are still but imperfectly understood. 



73. Investigation is of two kinds; analytical and synthetical: 

 and our inquiry observes these modes, whether it is conducted with 

 ocular testimonies, or by inference founded on analogy. 



74. The modes by which new forms are produced are two, 

 viz. by addition of properties or parts ; and by subtraction of pro- 

 perties or parts. The former gives what the subject of the addition* 

 or the other causes conjoined in the effect, did not before possess; 

 the latter leaves the subject such an identity as is determined by the 

 remaining causes. The proof of this proposition is, that an effect 

 will always remain the same if its present existence is not disturbed ; 

 and that no change can happen but by something added, or by 

 something taken away. 



75. Identity of effect requires identity of the causes. This is a 

 proposition to which there are many apparent exceptions, which 

 have never been explained ; it is my business to reconcile them, 

 a 



