A Tale of a Tub is Swift’s wildest adventure in satirical humor. Speaking through a diabolical persona of his own making, he pillories the corruptions of churches and schools. The title refers to the large tub that sailors would throw overboard to divert a whale from ramming their boat. In Swift’s satire, the whale is Thomas Hobbes’s Leviathan (1651), a political monster born of Descartes’s mathematical philosophy. Institutional Christianity is the ship that might be sunk in such an onslaught, and its timbers have already been loosened by schismatic factions.

The book is an allegory of church history. A father wills suits of clothes to his three sons, with directions that the suits never be altered. Brothers Peter, Martin, and Jack represent Catholic, Anglican, and Puritan sects, respectively. Peter upgrades his garments with gold lace, shoulder knots, and such trappings. Martin removes the false ornamentation from his without tearing the cloth. Jack zealously rips his garment to shreds to get rid of all ornament.

This basic allegory is richly embellished with outlandish digressions, parodies, puns, quibbles, unstructured foolery, and displays of odd erudition. The diabolical narrative takes every opportunity to prick the pretensions of pedants, religious dissenters, and perfectionists whose projects try to remake human society along rational lines. Swift thought that human reason is rather weak, blown flat in fact by the merest gust of desire, and so people should behave themselves and be governed by institutions such as the Church of England. Yet his diabolical narrator weakens this myth of order and reason by showing how vulnerable the mysteries of religion are to skeptical scrutiny.

Dressed in his sanctimonious vestments, Peter looks ridiculous issuing papal bulls on the superstitious doctrine that bread can be turned into mutton. The excesses of religious enthusiasts are reduced to absurdity in Jack’s rantings and in a scatological satire on a sect of Æolists, who believe that wind is the essence of all things, the original cause and first principle of the universe. In their most ridiculous rite, Æolists seat themselves atop barrels that catch the wind and blow inspiration into their posteriors by means of a secret funnel. Sacred sermons are delivered by their priests in oracular belches, or bursts of internal wind.

This maniacal conception reemerges in the famous Digression on Madness. There, the modern upsurges in religion, politics, and science are diagnosed as a form of madness, caused when the brain is intoxicated by vapors arising from the lower faculties. This vapor is to the brain what tickling is to the touch. Real perceptions are disordered in a happy confusion. Thus, happiness for moderns amounts to “a perpetual Possession of being well Deceived.” In the madhouse world of A Tale of a Tub, the modern man cut off from classical culture is lucky to be a fool among knaves, like the book’s demoniac narrator.