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



so vast and plain a practical distinction between living bodies and 

 those which do not live, is an ultimate fact ; indicating as such, 

 the existence of a broad line of demarcation between the subject- 

 matter of Biological and that of all other sciences. 



For I would have it understood that this simple Euglena is the 

 type of all living things, so far as the distinction between these 

 and inert matter is concerned. That cycle of changes, which is 

 constituted by perhaps not more than two or three steps in the 

 Euglena, is as clearly manifested in the multitudinous stages 

 through which the germ of an oak or of a man passes. Whatever 

 forms the Living Being may take on, whether simple or complex, 

 production, growth, reproduction, are the phenomena which dis 

 tinguish it from that which does not live. 



If this be true, it is clear that the student, in passing from 

 the physico-chemical to the physiological sciences, enters upon 

 a totally new order of facts ; and it will next be for us to con 

 sider how far these new facts involve new methods, or require a 

 modification of those with which he is already acquainted. 

 Now a great deal is said about the peculiarity of the scientific 

 method in general, and of the different methods which are 

 pursued in the different sciences. The Mathematics are said to 

 have one special method ; Physics another, Biology a third, and 

 so forth. For my own part, I must confess that I do not under 

 stand this phraseology. 



So far as I can arrive at any clear comprehension of the 

 matter, Science is not, as many would seem to suppose, a modi 

 fication of the black art, suited to the tastes of the nineteenth 

 century, and flourishing mainly in consequence of the decay of 

 the Inquisition. 



Science is, I believe, nothing but trained and organized 

 common sense, differing from the latter only as a veteran may 

 differ from a raw recruit : and its methods differ from those of 

 common sense only so far as the guardsman s cut and thrust 

 differ from the manner in which a savage wields his club. The 

 primary power is the same in each case, and perhaps the 

 untutored savage has the more brawny arm of the two. The 



