1 82 Heredity. 



after a hundred generations, here is indeed matter for reflection. 

 It may be said that heredity verifies in its own way the axiom, 

 Nothing is lost With its character of unconquerable firmness, of 

 obstinate persistency, it appears to us as one of those many inflex- 

 ible bonds by which omnipotent nature imprisons us in necessity. 

 We have now to see what attempt has been made to subject 

 the facts of heredity to the control of numbers. 



CHAPTER IIL 



ESSAYS IN STATISTICS. 

 I. 



IT is rightly said that there is no perfect ideal science except 

 that which is exact, that is to say, submitted to the control of 

 number, weight, and measure; but it is not correct to say that 

 there is no science save that which is exact Yet distinguished 

 and even eminent thinkers have maintained this paradox. If we 

 are to believe Herschel, ' no branch of human knowledge can be 

 considered as having left the state of infancy, if it does not base 

 its theories and correct them practically by means of numbers.' 

 If this be true, the domain of science at the present day would be 

 somewhat narrow. We should have to exclude from it a large 

 number of studies which rightly count as scientific, and even to 

 despair of ever bringing them under the conditions of science. 

 Admitting, what is probable, that certain branches of physics and 

 chemistry, at present refractory, may be subjected to all the strict- 

 ness of mathematical formulas, it is very doubtful whether the 

 facts of biology, and still more those of psychology and sociology, 

 can ever be so subjected. But it is not therefore necessary to 

 exclude them permanently from the domain of science. 



When we compare scientific knowledge with ordinary knowledge, 

 such as serves the ordinary needs of life, and when we consider the 

 nature of both, we find that they differ only in degree, that science 

 is not a mode of knowledge apart and sui generis, employing 

 processes exclusively its own, but that it springs from ordinary 

 knowledge by a natural evolution, tending always towards more 

 and more complex and more and more exact previsions, until 



