248 INDUCTION. 



continued in order to sustain it in the tube. This (it may be replied) is 

 because another force is acting without intermission, the force of gravity, 

 which would restore it to its level, unless counterpoised by a force equally 

 constant. But again: a tight bandage causes pain, which pain will some- 

 times go off as soon as the bandage is removed. The illumination which 

 the sun diffuses over the earth ceases when the sun goes down. 



There is, therefore, a distinction to be drawn. The conditions which are 

 necessary for the first production of a phenomenon, are occasionally also 

 necessary for its continuance ; though more commonly its continuance re- 

 quires no condition except negative ones. Most things, once produced, con- 

 tinue as they are, until something changes or destroys them ; but sonie re- 

 quire the permanent presence of the agencies which produced them at first. 

 These may, if we please, be considered as instantaneous phenomena, re- 

 quiring to be renewed at each instant by the cause by which they were at 

 first generated. Accordingly, the illumination of any given point of space 

 has always been looked upon as an instantaneous fact, which perishes and 

 is perpetually renewed as long as the necessary conditions subsist. If we 

 adopt this language we avoid the necessity of admitting that the continu- 

 ance of the cause is ever required to maintain the effect. We may say, it 

 is not required to maintain, but to reproduce, the effect, or else to coun- 

 teract some force tending to destroy it. And this may be a convenient 

 phraseology. But it is only a phraseology. The fact remains, that in 

 some cases (though those are a minority) the continuance of the conditions 

 which produced an effect is necessary to the continuance of the effect. 



As to the ulterior question, whether it is strictly necessary that the 

 cause, or assemblage of conditions, should precede, by ever so short an in- 

 stant, the production of the effect (a question raised and argued with much 

 ingenuity by Sir John Herschel in an Essay already quoted),* the inquiry 

 is of no consequence for our present purpose. There certainly are cases 

 in which the effect follows without any interval perceptible by our faculties ; 

 and when there is an interval, we can not tell by how many intermediate 

 links imperceptible to us that inverval maj^ really be filled up. But even 

 granting that an effect may commence simultaneously with its cause, the 

 view I have taken of causation is in no way practically affected. Wheth- 

 er the cause and its effect be necessarily successive or not, the begin- 

 ning of a phenomenon is what implies a cause, and causation is the law of 

 the succession of phenomena. If these axioms be granted, we can afford, 

 though I see no necessity for doing so, to drop the words antecedent and 

 consequent as applied to cause and effect. I have no objection to define a 

 cause, the assemblage of phenomena, which occurring, some other phenom- 

 enon invariably commences, or has its origin. Whether the effect coin- 

 cides in point of time with, or immediately follows, the hindmost of its 

 conditions, is immaterial. At all events, it does not precede it ; and when 

 we are in doubt, between two co-existent phenomena, which is cause and 

 which effect, we rightly deem the question solved if we can ascertain which 

 of them preceded the other. 



§ 8. It continually happens that several different phenomena, which are 

 not in the slightest degree dependent or conditional on one another, are 

 found all to depend, as the phrase is, on one and the same agent ; in other 

 words, one and the same phenomenon is seen to be followed by several 



* Essays, pp. 206-208. 



