PROGRESSIVE EFFECTS. 39 



first second, forty-eight in the second, and so on in 

 the ratio of the odd numbers, one, three, five, &c., is as 

 much an uniform sequence as that when the supports 

 are removed the body falls. The sequence of spring 

 and summer is as regular and invariable as that of 

 the approach of the sun and spring : but we do not 

 consider spring to be the cause of summer; it is 

 evident that they are both effects of the increased 

 heat received from the sun, and that if that cause did 

 not exist, spring might continue for ever, without 

 having the slightest tendency to produce summer. 

 As we have so often remarked, not the conditional, 

 but the unconditional invariable antecedent, is termed 

 the cause. That which would not be followed by 

 the effect unless something else had preceded, is not 

 the cause, however invariable the sequence may in 

 fact be. 



It is in this way that most of these uniformities 

 of succession are generated, which are not cases of 

 causation. When a phenomenon goes on increasing, 

 or periodically increases and diminishes, or goes 

 through any continued and unceasing process of 

 variation reducible to an uniform rule or law of 

 succession, we do not on this account presume that 

 any two successive terms of the series are cause and 

 effect. We presume the contrary ; we expect to find 

 that the whole series originates either from the con- 

 tinued action of fixed causes, or from causes which 

 go through a corresponding process of continuous 

 change. A tree grows from half an inch high to an 

 hundred feet; and some trees will generally grow to 

 that height unless prevented by some counteracting 

 cause. But we do not call the seedling the cause of 

 the full grown tree ; the invariable antecedent it cer- 

 tainly is, and we know very imperfectly upon what 



