MEASUREMENTS 207 



condition of truth, is an impossibility. Even if the ex 

 perience were repeated a million times over, and vouched 

 for by unimpeachable testimony, we should still be obliged 

 to reject it as either a fraud or an illusion. 



There is thus no mystery in the observation that a single 

 sequence in which both the antecedent and the consequent 

 have been perfectly defined is all that is required for the 

 establishment of a derivative law under the general law 

 of uniformity. The function of the rules of induction is 

 the discovery of sequences of this kind, that is in which both 

 the factors are exactly defined, and this function can never 

 be performed in such a way as to exclude all chance of error, 

 without the assistance of mathematical analysis. 



It is true that to speak of the elimination of all chances 

 of error is an exaggeration. In external, as well as in 

 internal nature, no two facts are exactly alike, and the law 

 of uniformity itself is only true as an abstract formula. 

 But it serves our purposes, and is the only guide we have 

 for the prediction of future events. The certainty of our 

 predictions is so vastly superior in respect to that kind of 

 facts which admit of mathematical analysis, that we are 

 as much justified in erecting them into a separate class, 

 and distinguishing them from other facts which do not 

 admit of mathematical analysis, as we are in distinguishing 

 plants from animals, notwithstanding our inability to lay 

 down an exact line of demarcation. To the second class, 

 that is to say to all the facts of our subjective nature, this 

 test of possibility is manifestly inapplicable, and, if we require 

 one, we must seek it elsewhere. 



The second of the two propositions that have been evolved 

 from the belief that fire burns is, that the fire causes the burn. 

 Into the voluminous discussions of which this proposition 

 has been the centre it is not necessary to descend. We 

 will only state shortly our own conclusions. An excellent 

 account of its origin is given by Cardinal Newman in the 

 following passage : 



The assent that we give to the proposition, as a first 

 principle, that nothing happens without a cause, is derived 



