have kept some subordinate taste
as a refreshment after their labours. Descartes went from the system
of the world to his flower-garden; Galileo used to read Ariosto; and
the metaphysical Dr. Clarke recovered himself from abstraction by
jumping over chairs and tables. The learned and indefatigable
chancellor d'Aguesseau declared, that change of employment was the
only recreation he ever knew. Even Montaigne, who found his recreation
in playing with his cat, educated himself better than those are
educated who go from intense study to complete idleness. It has been
very wisely recommended by Mr. Locke, that young people should early
be taught some mechanical employment, or some agreeable art, to which
they may recur for relief when they are tired by mental
application.[30]

Doctor Darwin supposes that "animal motions, or configurations of the
organs of sense, constitute our ideas.[31] The fatigue, he observes,
that follows a continued attention of the mind to one object, is
relieved by changing the subject of our thoughts, as the continued
movement of one limb is relieved by moving another in its stead." Dr.
Darwin has further suggested a tempting subject of experiment in his
theory of ocular spectra, to which we refer ingenious preceptors. Many
useful experiments in education might be tried upon the principles
which are there suggested. We dare not here trust ourselves to
speculate upon this subject, because we are not at present provided
with a sufficient number of facts to apply our theory to practice. If
we could exactly discover how to arrange mental employments so as to
induce actions in the antagonist faculties of the mind, we might
relieve it from fatigue in the same manner as the eye is relieved by
change of colour. By pursuing this idea, might we not hope to
cultivate the general power of attention to a degree of perfection
hitherto unknown?

We have endeavoured to show how, by different arrangements and proper
excitations, a preceptor may acquire that command over the attention
of his pupils, which is absolutely essential to successful
instruction; but we must recollect, that when the years commonly
devoted to education are over, when young people are no longer under
the care of a preceptor, they will continue to feel the advantages of
a command of attention, whenever they mix in the active business of
life, or whenever they apply to any profession, to literature, or
science. Their attention must now be enti