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, and of giving activity to their discoveries, by disclosing them to the people.  “Could I,” exclaims MONTESQUIEU, whose heart was beating with the feelings of a great author, “could I but afford new reasons to men to love their duties, their king, their country, their laws, that they might become more sensible of their happiness under every government they live, and in every station they occupy, I should deem myself the happiest of men!” Such was the pure aspiration of the great author who studied to preserve, by ameliorating, the humane fabric of society.  The same largeness of mind characterises all the eloquent friends of the human race.  In an age of religious intolerance it inspired the President DE THOU to inculcate, from sad experience and a juster view of human nature, the impolicy as well as the inhumanity of religious persecutions, in that dedication to Henry IV., which Lord Mansfield declared he could never read without rapture.  “I was not born for myself alone, but for my country and my friends!” exclaimed the genius which hallowed the virtuous pages of his immortal history.