Its mission is first to fix attention, and then to enlarge the circle of acquired knowledge.
A work which undertakes the refutation of vulgar prejudices, cannot have so high an aim.

It aspires only to clear the way for the steps of Truth; to prepare the minds of men to receive her; to rectify public opinion, and to snatch from unworthy hands dangerous weapons which they misuse.
It is above all, in social economy, that this hand-to-hand struggle, this ever-reviving combat with popular errors, has a true practical utility.
Sciences might be arranged in two categories.

Those of the first class whose application belongs only to particular professions, can be understood only by the learned; but the most ignorant may profit by their fruits.

We may enjoy the comforts of a watch; we may be transported by locomotives or steamboats, although knowing nothing of mechanism and astronomy.

We walk according to the laws of equilibrium, while entirely ignorant of them.
But there are sciences whose influence upon the public is proportioned only to the information of that public itself, and whose efficacy consists not in the accumulated knowledge of some few learned heads, but in that which has diffused itself into the reason of man in the aggregate.