The Art of Persuasion

No one is ignorant that there are two avenues by which opinions are received into the soul, which are its two principal powers: the understanding and the will. The more natural is that of the understanding, for we should never consent to any but demonstrated truths; but the more common, though the one contrary to nature, is that of the will; for all men are almost led to believe not of proof, but by attraction. This way is base, ignoble, and irrelevant: every one therefore disavows it. Each one professes to believe and even to love nothing but what he knows to be worthy of belief and love.