The defect seems to have come upon Spenser when it was too late to remedy it in the construction of his poem; and he adopted the somewhat clumsy expedient of telling us what the poem itself ought to have told us of its general story, in a letter to Sir Walter Ralegh. Ralegh himself, indeed, suggested the letter: apparently (from the date, Jan. 23, 1590), after the first part had gone through the press. And without this after-thought, as the twelfth book was never reached, we should have been left to gather the outline and plan of the story, from imperfect glimpses and allusions, as we have to fill up from hints and assumptions the gaps of an unskilful narrator, who leaves out what is essential to the understanding of his tale.
Incidentally, however, this letter is an advantage: for we have in it the poet's own statement of his purpose in writing, as well as a necessary sketch of his story. His allegory, as he had explained to Bryskett and his friends, had a moral purpose. He meant to shadow forth, under the figures of twelve knights, and in their various exploits, the characteristics of "a gentleman or noble person," "fashioned in virtuous and gentle discipline." He took his machinery from the popular legends about King Arthur, and his heads of moral philosophy from the current Aristotelian catalogue of the Schools.
Sir, knowing how doubtfully all Allegories may be construed, and this booke of mine, which I have entituled the Faery Queene, being a continued Allegory, or darke conceit, I haue thought good, as well for avoyding of gealous opinions and misconstructions, as also for your better light in reading thereof, (being so by you commanded,) to discover unto you the general intention and meaning, which in the whole course thereof I have fashioned, without expressing of any particular purposes, or by accidents, therein occasioned. The generall end therefore of all the booke is to fashion a gentleman or noble person in vertuous and gentle discipline: Which for that I conceived shoulde be most plausible and pleasing, being coloured with an historicall fiction, the which the most part of men delight to read, rather for variety of matter then for profite of the ensample, I chose the historye of King Arthure, as most fitte for the excellency of his person, being made famous by many mens former workes, and also furthest from the daunger of envy, and suspition of present time. In which I have followed all the antique Poets historicall; first Homere, who in the Persons of Agamemnon and Ulysses hath ensampled a good governour and a vertuous man, the one in his Ilias, the other in his Odysseis: then Virgil, whose like intention was to doe in the person of Aeneas: after him Ariosto comprised them both in his Orlando: and lately Tasso dissevered them againe, and formed both parts in two persons, namely that part which they in Philosophy call Ethice, or vertues of a private man, coloured in his Rinaldo; the other named Politice in his Godfredo. By ensample of which excellente Poets, I labour to pourtraict in Arthure, before he was king, the image of a brave knight, perfected in the twelve private morall vertues, as Aristotle hath devised; the which is the purpose of these first twelve bookes: which if I finde to be well accepted, I may be perhaps encoraged to frame the other part of polliticke vertues in his person, after that hee came to be king.