284 INFLUENCE OF HABIT. 



by a judicious and steady observance of the organic 

 laws in daily life, tban by exclusive attention to 

 any particular function to the neglect of all the 

 rest. 



It may be said that I allow nothing for the in- 

 fluence of habit in rendering situations and causes 

 comparatively innocuous, which were at first dan- 

 gerous. It is quite true that the human constitution 

 possesses a power of adapting itself, within certain 

 limits, to a change of circumstances ; but it is not 

 less true, that sudden and extreme changes often 

 destroy health and life before the system can adapt 

 itself to the exigency, and that after making the 

 most ample allowance for this source of safety, the 

 protection which it affords against the active causes 

 of disease is comparatively trifling. 



Where the change is sudden, as in passing from 

 * temperate to a tropical climate, or even from very 

 *ne to very inconstant weather, the consequences to 

 ealth are well known to be highly injurious. But 

 Inhere it is gradual and not extreme in degree, as in 

 passing from winter to summer, health is not much 

 endangered, because the system has time to accom- 

 modate itself to its new circumstances. Different 

 organs predominate in activity in different climates 

 and seasons, and time is thus required to admit of 

 the requisite changes taking place, without disturb- 

 ing the general balance of the circulation. In hot 

 countries, for example, the skin predominates greatly 

 in activity in comparison with the kidneys ; whereas, 

 in a cold country the case is precisely reversed. If, 

 therefore, a sudden transition be made from the one 

 to the other without due preparation, the rapid 

 change in the distribution of the blood from the sur- 

 face to the internal organs, or from the latter to the 

 surface, consequent on such change, is likely to be 

 attended with danger; although the same change 

 gradually effected would be unattended with any in- 

 jurious results. 



