In order to set this Matter in a clear Light to every Reader, I shall in the first Place observe, that a Metaphor is a Simile in one Word, which serves to convey the Thoughts of the Mind under Resemblances and Images which affect the Senses.  There is not any thing in the World, which may not be compared to several Things, if considered in several distinct Lights; or, in other Words, the same thing may be expressed by different Metaphors.  But the Mischief is, that an unskilful Author shall run these Metaphors so absurdly into one another, that there shall be no Simile, no agreeable Picture, no apt Resemblance, but Confusion, Obscurity, and Noise.  Thus I have known a Hero compared to a Thunderbolt, a Lion, and the Sea; all and each of them proper Metaphors for impetuosity, Courage or Force.  But by bad Management it hath so happened, that the Thunder-bolt hath overflowed its Banks; the Lion hath been darted through the Skies, and the Billows have rolled out of the Libyan Desart.

The Absurdity in this Instance is obvious.  And yet every time that clashing Metaphors are put together, this Fault is committed more or less.  It hath already been said, that Metaphors are Images of things which affect the Senses.  An Image therefore, taken from what acts upon the Sight, cannot, without Violence, be applied to the Hearing; and so of the rest.  It is no less an impropriety to make any Being in Nature or Art to do things in its Metaphorical State, which it could not do in its Original.  I shall illustrate what I have said by an Instance which I have read more than once in Controversial Writers. The heavy Lashes, saith a celebrated Author, that have dropped from your Pen, &c.  I suppose this Gentleman having frequently heard of Gall dropping from a Pen, and being lashed in a Satyr, he was resolved to have them both at any Rate, and so uttered this compleat Piece of Nonsense.  It will most effectually discover the Absurdity of these monstrous Unions, if we will suppose these Metaphors or Images actually Painted.  Imagine then a Hand holding a Pen, and several Lashes of Whip-cord falling from it, and you have the true Representation of this sort of Eloquence.  I believe, by this very Rule, a Reader may be able to judge of the Union of all Metaphors whatsoever, and determine which are Homogeneous and which Heterogeneous:  or to speak more plainly, which are Consistent, and which Inconsistent.

There is yet one Evil more which I must take notice of, and that is the running of Metaphors into tedious Allegories; which, though an Error on the better Hand, causes Confusion as much as the other.  This becomes abominable, when the Lustre of one Word leads a Writer out of his Road, and makes him wander from his Subject for a Page together.  I remember a young Fellow, of this Turn, who having said by Chance that his Mistress had a World of Charms, thereupon took Occasion to consider her as one possessed of Frigid and Torrid Zones, and pursued her from the one Pole to the other.  I shall conclude this Paper with a Letter written in that enormous Style, which I hope my Reader hath by this time set his Heart against.  The Epistle hath heretofore received great Applause; but after what hath been said, let any Man commend it if he dare.