Syrian and Arabian Deities enabled
MILTON to comprise, in one hundred and thirty beautiful lines, the two
large and learned syntagma which Selden had composed on that abstract
subject. LELAND, the father of British antiquities, impelled STOWE to work
on his "Survey of London;" and Stowe's "London" inspired CAMDEN'S
stupendous "Britannia." Herodotus produced Thucydides, and Thucydides
Xenophon. With us HUME, ROBERTSON, and GIBBON rose almost simultaneously
by mutual inspiration. There exists a perpetual action and reaction in the
history of the human mind. It has frequently been inquired why certain
periods seem to have been more favourable to a particular class of genius
than another; or, in other words, why men of genius appear in clusters. We
have theories respecting barren periods, which are only satisfactorily
accounted for by moral causes. Genius generates enthusiasm and rivalry;
but, having reached the meridian of its class, we find that there can be
no progress in the limited perfection of human nature. All excellence in
art, if it cannot advance, must decline.

Important discoveries are often obtained by accident; but the single work
of a man of genius, which has at length changed the character of a people,
and even of an age, is slowly matured in meditation. Even the mechanical
inventions of genius must first become perfect in its own solitary
abode ere the world can possess them. Men of genius then produce their
usefulness in privacy; but it may not be of immediate application, and is
often undervalued by their own generation.

The influence of authors is so great, while the author himself is so
inconsiderable, that to some the cause may not appear commensurate to its
effect. When EPICURUS published his doctrines, men immediately began to
express themselves with freedom on the established religion, and the dark
and fearful superstitions of paganism, falling into neglect, mouldered
away. If, then, before the art of multiplying the productions of the human
mind existed, the doctrines of a philosopher in manuscript or by lecture
could diffuse themselves throughout a literary nation, it will baffle the
algebraist of metaphysics to calculate the unknown quantities of the
propagation of human thought. There are problems in metaphysics, as well
as in mathematics, which can never be resolved.

A small portion of mankind appears marked out by nature and by study for
the purpose of cultivating their thoughts in peace,