328 PROFESSOR WHEWELL, ON CAUSE AND EFFECT. 



the progressive effect is simultaneous, step by step, with the progressive 

 eause. There is a series of operations ; as for instance, intussusception, 

 digestion, assimilation, growth : each of these is a progressive operation ; 

 and in the progress of each operation, the steps of the effect and the 

 instantaneous forces are simultaneous. But the end of one operation 

 is the beginning of the next, or at least in part, and hence we have 

 time occupied by the succession. The end of intussusception is the be- 

 ginning of digestion, the end of digestion the beginning of assimilation, 

 and so on. These aggregate effects succeed each other; and hence 

 growth is subsequent to the taking of food ; though each instantaneous 

 force of animal life, no less than of mechanism, produces an effect 

 simultaneous with its action. Each of these separate operations is an 

 aggregate operation, and occupies time; and each aggregate effect is a 

 condition of the action of the cause in the next operation. 



Again ; if an animal in a permanent condition, neither waxing nor 

 wasting, may be taken as the normal state in which the functions of life 

 measure time, in order that we may consider growth as an effect, to be 

 referred to food as cause; we may, for other purposes, consider, as the 

 normal condition, an animal waxing and then wasting, according to the 

 usual law of animal life : and we must take this, the healthy progress of 

 an animal, as our normal condition, if we have to consider causes which 

 produce disease. If we have to refer the morbid condition of an animal 

 to the influence of poison, for example, we must consider how far the 

 condition deviates from what it would have been if the poison had not 

 been taken into the frame. The usual progress of the animal func- 

 tions including its growth, is the measure of time; the deviation from 

 this usual progress is the indication of cause; and the effect of the poi- 

 son is subsequent to the cause, because the poison acts through the 

 cycle of the animal functions just mentioned, which occupies time ; and 

 because the taking the poison into the system, not any subsequent 

 action of the animal forces in the system, is considered as the event 

 which we must contemplate as a cause. To resume the analogy of the 

 clock : the rate of the clock is altered by altering the parts ; but this 

 alteration itself may occupy time ; as if we alter the rate of a clock 

 by applying a drop of acid, which gradually eats off a part of the 



