U>0 PSYCIJ0L06T. 



folded already. This saving of trouble is due to the essential nature ot 

 habit, which brings it about that, to reproduce the effect, a less anicnint 

 of the outward cause is required. Tiie sounds of a violin improve by 

 use in the hands of an able artist, because the fibres of the wood at last 

 contract habits of vibration conformed to harmonic relations. This is 

 what gives such inestimable value to instruments that have belonged to 

 great masters. Water, in flowing, hollows out for itself a channel, wliich 

 grows broader and deeper; and, after having ceased to flow, it resumes, 

 when it flows again, tlie path traced by itself before. Just so, the im- 

 pressions of outer objects fashion for themselves in the nervous system 

 more and moi-e appropriate paths, and these vital phenomena recur 

 under similar excitements from without, when they have been inter- 

 rupted a certain time." * 



Not in the nervous system alone. A scar anywhere is 

 a locus minoris resistenticp, more liable to be abraded, 

 inflamed, to sufler pain and cold, than are the neighboring 

 parts. A sprained ankle, a dislocated arm, are in danger 

 of being sprained or dislocated again ; joints that have once 

 been attacked by rheumatism or gout, mucous membranes 

 that have been the seat of catarrh, are with each fresh re- 

 currence more prone to a relapse, until often the morbid 

 state chronicall}^ substitutes itself for the sound one. And 

 if we ascend to the nervous system, we find how many so- 

 called functional diseases seem to keep themselves going 

 simply because they happen to have once begun ; and how 

 the forcible cutting short by medicine of a few attacks is 

 often sufficient to enable the physiological forces to get pos- 

 session of the field again, and to bring the organs back to 

 functions of health. Epilepsies, neuralgias, convulsive afl"ec- 

 tions of various sorts, insomnias, are so many cases in j)oiut. 

 And, to take what are more obviously habits, the success 

 with which a 'weaning' treatment can often be applied to 

 the victims of unhealthy indulgence of jDassioil, or of 

 mere complaining or irascible disposition, shows us how 

 much the morbid manifestations themselves were due to the 

 mere inertia of the nervous organs, when once launched on 

 a false career. 



Can we now form a notion of what the inward physical 

 changes may be like, in organs whose habits have thus 



* Revue Philosophique, i, 324. 



