freshness and vigor that is surprising after the previous lassitude._

Nor is this all. The same process may be repeated a second time and a
third time, each new effort of the will being followed by a renewal of
energy.

[Sidenote: _Reserve Supplies of Power_]

Many a man will tell you that he does his best work in the wee watches
of the morning, after tedious hours of persevering but fruitless
effort. Instead of being exhausted by its long hours of persistent
endeavor, the mind seems now to rise to the acme of its power, to
achieve its supreme accomplishments. Difficulties melt into thin air,
profound problems find easy solution. Flights of genius manifest
themselves. Yet long before midnight such a one had perhaps felt
himself yield to fatigue and had tied a wet towel around his head or
had taken stimulants to keep himself awake.

The existence of this reserve supply of energy is manifested in
physical as well as mental effort.

Men who work with their heads and men who work with their hands,
scholars and Marathon runners, must alike testify to the existence of
_reserve supplies of power not ordinarily drawn upon_.

[Sidenote: _"Blue" Mondays_]

If we do not always or habitually utilize this reserve power, it is
simply because we have accustomed ourselves to yield at once to the
first strong feeling of fatigue.