xxvii.] GENERALISATION. 621 



the tides is interrupted by an enormous irregular wave, we 

 attribute it to an earthquake, or some gigantic natural dis- 

 turbance. If a meteoric stone falls upon a person and kills 

 him, it is clearly a discontinuity in his life, of which he 

 could have had no anticipation. A sudden sound may pass 

 through the air neither preceded nor followed by any con- 

 tinuous effect. Although, then, we may regard the Law of 

 Continuity as a principle of nature holding rigorously true 

 in many of the relations of natural forces, it seems to be a 

 matter of difficulty to assign the limits within which the 

 law is verified. Much caution is required in its applica- 

 tion. 



Negative Arguments on the Principle of Continuity. 



Upon the principle of continuity we may sometimes 

 found arguments of great force which prove an hypothesis 

 to be impossible, because it would involve a continual re- 

 petition of a process ad infinitum, or else a purely arbitrary 

 breach at some point. Bonnet's famous theory of reproduc- 

 tion represented every living creature as containing germs 

 which were perfect representatives of the next generation, 

 so that on the same principle they necessarily included 

 germs of the next generation, and so on indefinitely. The 

 theory was sufficiently refuted when once clearly stated, 

 as in the following poem called the Universe, 1 by Henry 

 Baker : 



" Each seed includes a plant : that plant, again, 

 Has other seeds, which other plants contain : 

 Those other plants have all their seeds, and those 

 More plants again, successively inclose. 



" Thus, ev'ry single berry that we find, 

 Has, really, in itself whole forests of its kind, 

 Empire and wealth one acorn may dispense, 

 By fleets to sail a thousand ages hence." 



The general principle of inference, that what we know 

 of one case must be true of similar cases, so far as they 

 are similar, prevents Our asserting anything which we can- 

 not apply time after time under the same circumstances. 



1 Philosophical Transactions (1740), vol. xli. p. 454. 



