OEIGIN OF DISEASE AND THE GERM THEORY. 131 



to this, viz. the highest provisional rationale which the mind of 

 man has grasped. Indeed, it may be said to be a universal law of 

 causation. Naturally it was first recognised where most easily 

 perceived, and only in quite recent times has the idea of definite 

 causation been traced into the sphere of vital actions, a sphere 

 which necessarily was at first replete with doubt and mystery. In 

 view of the mass of evidence now at our disposal, it may be said 

 that although the theory does not always strike us as being in 

 complete accord with all the observed and multifarious facts of 

 life, yet, nevertheless, the closest examination of difficult points 

 will invariably reveal that what aspects of life are involved in the 

 folds of the inexplicable are certainly of no greater magnitude 

 than are the other equally inscrutable mysteries presented by 

 many of the inanimate aggregates existing in the universe. In 

 other words, it may once for all be admitted that, so far as the 

 need for explanation of their origin and existence is concerned, 

 living beings cannot now be looked upon as oflering greater 

 difficulties than do the Heavenly bodies, for instance. No doubt 

 at first sight the various processes displayed by living organisms 

 are apparently more wonderful than are the other kinds of 

 phenomena presented on all sides to our consciousness ; but in 

 proportion as by studious investigation we gradually become 

 more and more familiar with life as displayed by the innumerable 

 hving things around us in earth, sea, and sky, the great question 

 cannot but present itself whether the marvellously-regulated 

 motions of the heavenly bodies, and even the bnre existence of 

 them throughout the starry spaces of the heavens, is in essential 

 reality one whit less wonderful than is the conscious existence 

 of any human being. In short, the systematic explanation of all 

 things according to the idea of a gradual evolution of them, i,e. 

 according to a universal law of causation, is a very great advance 

 in our methods of reasoning on the erratic and confused concep- 

 tions which were formerly held in respect to the phenomena 

 occurring around us. Furthermore, it must be sufficiently 

 obvious that, since changes or functions displayed by organisms 

 which depart so far from those of health as to be called abnor- 

 mal, can only be classed as part and parcel of the sum total of 

 processes manifested by them, they, too, can have no other than 

 a similar relative explanation. 



Hence it follows that the idea of evolution in the field of 



9 * 



