These different kinds of allusion are but so many different manners of similitude; and, that they may please the imagination, the likeness ought to be very exact or very agreeable, as we love to see a picture where the resemblance is just, or the posture and air graceful. But we often find eminent writers very faulty in this respect: great scholars are apt to fetch their comparisons and allusions from the sciences in which they are most conversant, so that a man may see the compass of their learning in a treatise on the most indifferent subject. I have read a discourse upon love, which none but a profound chemist could understand, and have heard many a sermon that should only have been preached before a congregation of Cartesians.

The Fashionable American Letter Writer: or, The Art of Polite Correspondence (1833).