68 LAY SERMONS, ESSAYS, AND REVIEWS. [v. 



Now, this phrase &quot; inexact &quot; must refer either to the methods 

 or to the results of Physiological science. 



It cannot be correct to apply it to the methods ; for, as I hope 

 to show you by and by, these are identical in all sciences, and 

 whatever is true of Physiological method is true of Physical and 

 Mathematical method. 



Is it then the results of Biological science which are &quot; inexact &quot; ? 

 I think not. If I say that respiration is performed by the lungs ; 

 that digestion is effected in the stomach ; that the eye is the 

 organ of sight ; that the jaws of a vertebrated animal never open 

 sideways, but always up and down ; while those of an annulose 

 animal always open sideways, and never up and down I am 

 enumerating propositions which are as exact as anything in 

 Euclid. How then has this notion of the inexactness of Bio 

 logical science come about ? I believe from two causes : first, 

 because, in consequence of the great complexity of the science 

 and the multitude of interfering conditions, we are very often 

 only enabled to predict approximately what will occur under 

 given circumstances ; and secondly, because, on account of the 

 comparative youth of the Physiological sciences, a great many of 

 their laws are still imperfectly worked out. But, in an educa 

 tional point of view, it is most important to distinguish between 

 the essence of a science and the accidents which surround it ; 

 and essentially, the methods and results of Physiology are as 

 exact as those of Physics or Mathematics. 



It is said that the Physiological method is especially compa 

 rative l ; and this dictum also finds favour in the eyes of many. 



1 &quot; In the third place, we have to review the method of Comparison, which 

 is so specially adapted to the study of living bodies, and by which, above all 

 others, that study must be advanced. In Astronomy, this method is neces 

 sarily inapplicable ; and it is not till we arrive at Chemistry that this third 

 means of investigation can be used, and then only in subordination to the 

 two others. It is in the study, both statical and dynamical, of living bodies 

 that it first acquires its full development ; and its use elsewhere can be only 

 through its application here.&quot; COMTE S Positive Philosophy, translated by 

 Miss Martineau. Vol. i. p. 372. 



By what method does M. Comte suppose that the equality or inequality of 

 forces and quantities and the dissimilarity or similarity of forms points of 

 some slight importance not only in Astronomy and Physics, but even in 

 Mathematics are ascertained, if not by Comparison ? 



