The Chaucer Review: An Indexed Bibliography (Vols. 1-30)

Ireland, Richard W. "Chaucer's Toxicology." 29 (1994): 74-92.
Both the Pardoner's Tale and the Parson's Tale refer to poisoning. Medieval Christians associated poison with sin as do the Book of Vices and Virtues and the Ancrene Riwle. In the Leges Henrici Primi poisoning is associated with witchcraft. In the Pardoner's Tale Chaucer connects poisoning to the devil, although the young man obtains the poison by merely visiting an apothecary. The swelling identified with poisoning is often presented as beyond the bounds of medical knowledge and is, therefore, attributable to the devil. The Parson also discusses poisoning as an abortive method. John Myrc's Instructions for Parish Priests and the Ancrene Riwle both refer to such activity as sin, again linking poisoning to the devil. Abortive activity was also considered a matter for civil court, though the general absence of such cases indicates the difficulty lawyers had with them. Chaucer uses poisoning in the Pardoner's Tale to connect true Christianity to false religion and the dangers inherent in such falsehood.