ir vehement
stimulating effect, which still has power to rouse the excitability
to action, though it has been considerably exhausted. The best method
of inducing sleep, in these cases, is to endeavour to withdraw the
mind from these impressions, particularly from uneasy emotions, by
employing it on something that makes a less impression, and which
does not require much exertion, or produce too much commotion; such
as counting to a thousand, or counting drops of water which fall
slowly; by listening to the humming of bees, or the murmuring of a
rivulet. Virgil describes a situation fitted to induce sleep, most
beautifully, in the following words.

"Fortunate senex, hic inter flumina nota,
Et fontes sacros, frigus captabis opacum.
Hinc tibi, quae semper vicino ab limite sepes
Hyblaeis apibus florem depasta salicti,
Seape levi somnum suadebit inire susurro."

In infancy much sleep is required; the excitability, being then
extremely abundant, is soon exhausted by external stimulants, and
therefore soon requires renewing or accumulating; on this account,
during the first five or six months of their life, children require
this mode of renewing their exhausted excitability several times in
the day; as they advance in years, and as this excess of excitability
is exhausted by the application of stimulants, less sleep is
required: in the prime of life least of all is necessary. There is
great difference however, in this respect, in different
constitutions. Some persons are sufficiently refreshed by three or
four hours sleep, while others require eight or ten hours. More
however depends, in my opinion, on the mode of living. Those who
indulge in the use of spirituous or fermented liquors, which exhaust
the excitability to a great degree, require much more sleep than
those who are content with the crystal stream. The latter never feel
themselves stupid or heavy after dinner, but are immediately fit to
engage in study or business. As age advances, more sleep is again
required; and the excitability at last becomes so far exhausted, and
the system so torpid, that the greatest portion of gradually expiring
life is spent in sleep.

Temperance and exercise are the most conducive to sound healthy
sleep, hence the peasant is rewarded, for his toil and frugal mode of
life, with a blessing, which is seldom enjoyed by those whom wealth
renders indolent and luxurious. The poor in the country enjoy sound
and sweet sleep: fo