152 COSMIC PHILOSOPHY. [pt. i. 



only when, some third circumstance also exists, is not the 

 cause, even though no case should ever have occuired in 

 which the phenomenon took place without it." Now, either 

 day or night " might have existed for any length of time, and 

 the other not have followed the sooner for its existence : day* 

 follows night only if certain other antecedents [the presence 

 of the sun above the horizon, and the absence of any eclipsing 

 opaque body from the direct path of the solar rays] exist ; 

 and where those antecedents existed, it would follow in any 

 case. No one, probably, ever called night the cause of day ; 

 mankind must so soon have arrived at the very obvious 

 generalization, that the state of general illumination which 

 we call day would follow from the presence of a sufficiently 

 luminous body, whether darkness had preceded or not." 



Mr. Mill's further explanation of this point is so luminous 

 that I prefer to cite it in his own words, rather than to 

 abridge and dilute it. " To some," says Mr. Mill, " it may 

 appear that the sequence between night and day being in- 

 variable in our experience, we have as much ground in this 

 case as experience can give in any case, for recognizing the 

 two phenomena as cause and effect; and that to say that 

 more is necessary — to require a belief that the succession is 

 unconditional, or in other words that it would be invariable 

 under all changes of circumstances, is to acknowledge in 

 causation an element of belief not derived from experience. 

 The answer to this is, that it is experience itself which 

 teaches us that one uniformity of sequence is conditional 

 and another unconditional. When we judge that the succes- 

 sion of night and day is a derivative sequence, depending on 

 something else, we proceed on grounds of experience. It is 

 the evidence of experience which convinces us that day could 

 equally exist without being followed by night, and that night 

 could equally exist without being followed by day. To say 

 that these beliefs ' are not generated by our mere observation 

 of sequence,' ia to forget that twice in every twenty-fou 



