2 METHODOLOGICAL INTRODUCTION. 



different directions. In the first place, too little attention has been 

 directed to the laws of a true natural philosophy, whose simplest rules 

 have in many cases been wholly disregarded ; in the next place, the 

 necessary causal connexion existing between chemistry and phy- 

 siology, as well as between histology and pathological anatomy, 

 has too often been entirely neglected ; and lastly, much miscon- 

 ception has arisen from the assumption that chemistry afforded a 

 satisfactory solution to many questions which it is either wholly 

 incompetent to answer, or which must at all events remain undecided 

 in the present state of our knowledge. 



While we still find occasion to deplore the absence of the 

 steady influence of a true natural philosophy in the application of 

 chemistry to the science of general life, we do not refer to any of 

 those nearly exploded systems of natural science which may be 

 regarded almost in the light of poetic fictions, but to that Newto- 

 nian method of contemplating nature, which has carried Astronomy 

 to its present high state of perfection, and has led to the most 

 brilliant discoveries in physics. It is this method of viewing nature 

 which Fries alone understood how to raise into a system, and to 

 which the immortal Humboldt has given life and expression in his 

 ' Cosmos/ It is only by the application of abstract physical laws, 

 by the establishment of certain momenta of empirically observed 

 phenomena, and by a steady adherence to safely guiding maxims, 

 in short, by logical sequence, that we can advance in the inves- 

 tigation of vital phenomena. It would almost seem as if medicine, 

 in the earlier periods of its history, had cast a shadow over those 

 kindred sciences which are able to afford it aid and support, 

 clouding even their brightest points. It has thus been found 

 impracticable at once to rid medicine, notwithstanding its assumed 

 physiological character, of the mania of attempting to explain every- 

 thing by the old system of hypotheses ; and hence this science has 

 derived less benefit than many others from the exact method of 

 physical enquiry, having simply borrowed certain materials from 

 chemistry and the kindred natural sciences, and substituted, in the 

 place of the older vagaries of natural philosophy, various chemical 

 phrases and high sounding terms, scarcely less devoid of true import 

 than the former. This deficiency in logical sequence, which we so 

 frequently at present encounter in medicine, has unfortunately also 

 infected animal chemistry ; for here likewise facts have not been 

 sufficiently distinguished from hypotheses, or hypothesis fromfiction. 

 This is more easily accounted for in physiological than in pure general 

 chemistry : for while the latter treats almost exclusively of palpable 



