Sir Walter Scott on Gulliver’s Travels: (from Scott’s introduction to his edition of Swift, 1824)

The Voyage to the Land of the Houyhnhnms, is, beyond contest, the basest and most unworthy part of the work.  It holds mankind forth in a light too degrading for contemplation, and which, if admitted, would justify or palliate the worst vices, by exhibiting them as natural attributes, and rendering reformation from a state of such base depravity a task to desperate to be attempted. As no good could possibly be attained by the exhibition of so loathsome a picture of humanity, as it may even tend to great evil, by removing every motive for philanthropy, the publication has been justly considered as a stain upon the character of the ingenious author… As the previous departments of the satire were leveled against the court of George I, against statesmen, and against philosophers, the wider sweep of this last division comprehends human nature in every stage and variety, and, with an industry as malicious as the author’s knowledge of life is extensive, holds it up to execration in all.

It is in some consolation to remark, that the fiction on which this libel on human nature rests, is, in every respect, gross and improbable, and far, from being entitled to praise due to the management of the first two parts, is inferior in plan even to the third. The voyage to Laputa, if we except the flying island, which has often been regarded as an unnecessary violation of the laws of nature, the picture of the Struldbrugs, and the powers of the governor of Balnibarbi, (from both of which an excellent moral is extracted,) falls within the rank of such ideal communities as the republic of Plato and the Utopia of Sir Thomas Moore. But the state of the Houyhnhnms is not only morally but physically impossible, and, as Dr. Beattie has remarked, self-contradictory also, since these animals are represented with attributes inconsistent with their natural structure…

(Norton ed. 318)