LAW OF CAUSATION. 397 



concern myself are not efficient, but physical causes. 

 They are causes in that sense alone, in which one 

 physical fact may be said to be the cause of another. 

 Of the efficient causes of phenomena, or whether any 

 such causes exist at all, I am not called upon to give 

 an opinion. The notion of causation is deemed, by 

 the schools of metaphysics most in vogue at the 

 present moment, to imply a mysterious and most 

 powerful tie, such as cannot, or at least does not, 

 exist between any physical fact and that other phy- 

 sical fact upon which it is invariably consequent, and 

 which is popularly termed its cause : and thence is 

 deduced the supposed necessity of ascending higher, 

 into the essences and inherent constitution of things, to 

 find the true cause, the cause which is not only followed 

 by, but actually produces, the effect. No such necessity 

 exists for the purposes of the present inquiry, nor 

 will any such doctrine be found in the following pages. 

 But neither will there be found anything incompatible 

 with it. We are in no way concerned in the question. 

 The only notion of a cause, which the theory of induc- 

 tion requires, is such a notion as can be gained from 

 experience. The Law of Causation, the recognition 

 of which is the main pillar of inductive philosophy, 

 is but the familiar truth, that invariability of succes- 

 sion is found by observation to obtain between every 

 fact in nature and some other fact which has pre- 

 ceded it ; independently of all consideration respecting 

 the ultimate mode of production of phenomena, and 

 of every other question regarding the nature of 

 " Things in themselves." 



Between the phenomena, then, which exist at any 

 instant, and the phenomena which exist at the suc- 

 ceeding instant, there is an invariable order of succes- 

 sion ; and, as we said in speaking of the general 



