Page:Popular Science Monthly Volume 10.djvu/534

516 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 reflection, he can still keep a watch 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 nervous power.

From this estimate of comparative outlay, we may judge what are the times and seasons and circumstances most favorable to acquirement. 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 remission 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, although the constructive and routine efforts may still be kept up.

The regular course of the day may be interfered with by exceptional 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 advances, 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 disturbing 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