5 i6 THE POPULAR SCIENCE MONTHLY. 



ing and noting. This needs a certain strain of attention ; it is not 

 possible in the very lowest tide of the nervous flow ; but it may be 

 carried on with all but the smallest degrees of brain-power. When 

 the scholar or the man of science ceases to trust his memory implicitly 

 for retaining new facts that occur in his reading, observation, or re- 

 flection, he can still keep a w r atch for them, and enter them in his 

 notes. So in the hours of the day when memory is less to be trusted, 

 useful study may still be maintained by the help of the memorandum 

 and the note-book. 



The indulgence of the emotions (when not violent or excessive) is 

 about the least expensive of our mental exercises, and may go on when 

 we are unfit for any of the higher intellectual moods, least of all for 

 the crowning work of storing up new knowledge or new aptitudes. 

 There are degrees here also; but, speaking generally, to love or to 

 hate, to dominate or to worship, although impossible in the lowest 

 depths of debility, are within the scope of the inferior grades of ner- 

 vous power. 



From this estimate of comparative outlay, we may judge what are 

 the times and seasons and circumstances most favorable to acquire- 

 ment. It may be assumed that in the early part of the day the total 

 energy of the system is at its height, and that toward evening it flags; 

 hence morning is the season of improvement. For two or three hours 

 after the first meal, the strength is probably at the highest; total re- 

 mission for another hour or two, and a second meal (with physical 

 exercise when the labor has been sedentary), prepares for a second 

 display of vigor, although presumably not equal to the first; when the 

 edge of this is worn off, there may, after a pause, be another bout of 

 application, but far inferior in result to the first or even to the second. 

 No severe strain should be attempted in this last stage; not much 

 stress should be placed on the available plasticity of the system, al- 

 though the constructive and routine efforts may still be kept up. 



The regular course of the day may be interfered with by excep- 

 tional circumstances, but these only confirm the rule. If we have lain 

 idle or inactive for the early hours, we may of course be fresher in the 

 evening, but the late application will not make up for the loss of the 

 early hours; the nervous energy will gradually subside as the day ad- 

 vances, however little exertion we may make. Again, we may at any 

 time determine an outburst of nervous energy by persistent exercise 

 and by stimulation, which draws blood to the brain, without regard 

 to circumstances and seasons, but this is wasteful in itself and disturb- 

 ing to the healthy functions. 



As a general rule, the system is at its greatest vigor in the cold 

 season of the year; and most work is done in winter. Summer studies 

 are comparatively unproductive. 



The review of the varying plasticity in the different stages of life 

 might be conducted on the same plan of estimating the collective 



