qr CRITICISMS ON “THE ORIGIN OF SPECIES” 83 
or organism (A) is precisely fitted to perform a 
function or purpose (B) ; therefore it was specially 
constructed to perform that function. In Paley’s 
famous illustration, the adaptation of all the parts 
of the watch to the function, or purpose, of showing 
the time, is held to be evidence that the watch 
- was specially contrived to that end; on the ground, 
that the only cause we know of, competent to 
_ produce such an effect as a watch which shall keep 
time, is a contriving intelligence adapting the 
means directly to that end. 
Suppose, however, that any one had been able 
to show that the watch had not been made directly 
by any person, but that it was the result of the 
modification of another watch which kept time but 
poorly ; and that this again had proceeded from a 
structure which could hardly be called a watch 
at all—seeing that it had no figures on the dial 
and the hands were rudimentary ; and that going 
_back and back in time we came at last to a re- 
volving barrel as the earliest traceable rudiment 
of the whole fabric. And imagine that it had 
been possible to show that all these changes 
had resulted, first, from a tendency of the structure 
to vary indefinitely ; and secondly, from something 
Se utounding word which helped all variations 
in the direction of an accurate time-keeper, and 
checked all those in other directions ; then it is 
obvious that the force of Paley’s argument would 
be gone. For it would be demonstrated that an 
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