Henry Fielding’s The History of Tom Jones, a Foundling (1749) is long novel, and to many critics the novel with the most perfect plot. But what the reason I always revisit it is for the chapter preambles that Fielding included to elucidate on the novel as a genre.
In the excerpt that follows Fielding writes with some humor the dangers for writers of appealing to supernatural agents. Actually he is quite clear in issuing a warning that going outside the realm of possibility exposes the writer to ridicule and derision. So, beware of ghosts, miracles, fairies—and the like.
... I think it may very reasonably be required of every writer, that he keeps within the bounds of possibility; and still remembers that what it is not possible for man to perform, it is scarce possible for man to believe he did perform.
This conviction perhaps gave birth to many stories of the ancient heathen deities (for most of them are of poetical original). The poet, being desirous to indulge a wanton and extravagant imagination, took refuge in that power, of the extent of which his readers were no judges, or rather which they imagined to be infinite, and consequently they could not be shocked at any prodigies related of it. This hath been strongly urged in defense of Homer's miracles; and it is perhaps a defense; not, as Mr. Pope would have it, because Ulysses told a set of foolish lies to the Phaeacians, who were a very dull nation; but because the poet himself wrote to heathens, to whom poetical fables were articles of faith.
For my own part, I must confess, so compassionate is my temper, I wish Polypheme had confined himself to his milk diet, and preserved his eye; nor could Ulysses be much more concerned than myself, when his companions were turned into swine by Circe, who showed, I think, afterwards, too much regard for man's flesh to be supposed capable of converting it into bacon.
I wish, likewise, with all my heart, that Homer could have known the rule prescribed by Horace, to introduce supernatural agents as seldom as possible. We should not then have seen his gods coming on trivial errands, and often behaving themselves so as not only to forfeit all title to respect, but to become the objects of scorn and derision. A conduct which must have shocked the credulity of a pious and sagacious heathen; and which could never have been defended, unless by agreeing with a supposition to which I have sometimes almost inclined, that this most glorious poet, as he certainly was, had an intent to burlesque the superstitious faith of his own age and country.
But I have rested too long on a doctrine which can be of no use to a Christian writer; for as he cannot introduce into his works any of that heavenly host which make a part of his creed, so it is horrid puerility to search the heathen theology for any of those deities who have been long since dethroned from their immortality.
Lord Shaftesbury observes that nothing is more cold than the invocation of a muse by a modern; he might have added, that nothing can be more absurd. A modern may with much more elegance invoke a ballad, as some have thought Homer did, or a mug of ale, with the author of Hudibras; which latter may perhaps have inspired more poetry, as well as prose, than all the liquors of Hippocrene or Helicon.
The only supernatural agents which can in any manner be allowed to us moderns, are ghosts; but of these I would advise an author to be extremely sparing. These are indeed, like arsenic, and other dangerous drugs in physic, to be used with the utmost caution; nor would I advise the introduction of them at all in those works, or by those authors, to which, or to whom, a horse-laugh in the reader would be any great prejudice or mortification.
As for elves and fairies, and other such mummery, I purposely omit the mention of them, as I should be very unwilling to confine within any bounds those surprising imaginations, for whose vast capacity the limits of human nature are too narrow; whose works are to be considered as a new creation; and who have consequently lust right to do what they will with their own.
Man, therefore, is the highest subject (unless on very extraordinary occasions indeed) which presents itself to the pen of our historian, or of our poet; and in relating his actions, great care is to be taken that we do not exceed the capacity of the agent we describe.
Henry Fielding. The History of Tom Jones, a Foundling (1749) Book VIII, Chapter i.