Note 47 — Chapter V · OF THE VERB.
Reading edition
Though the authority of Milton, Dryden, Pope, and Swift, can be pleaded in favour of wert, as the second person singular of this tense, I am inclined to agree with Lowth, that in conformity to analogy, as well as the practice of the best ancient writers, it would be better to confine wert to the imperfect conditional.