This chapter considers the two cases of lying and sexuality partly because of their intrinsic interest, and because they let us see some of the strengths and weaknesses of Thomas's methodology in philosophical areas. Following the discussion of lying, the chapter looks briefly at Thomas on the topic of unnatural sins and the use of 'natural' in ethics. Thomas's views are strongly attacked in Drury 2008, and the chapter considers the acceptability or otherwise of Thomas's views, the central concern is with his philosophical method. Thomas is strongly influenced by Augustine, who has two works which deal centrally with lying, On Lying, and Against Lying. Augustine is clear that you must not lie merely to save someone's life. Thomas picks out various sexual doings as sinful. Interestingly, in the 'Supplement' to ST, Thomas explores whether it is lawful for a man to kill his wife if she be discovered in the act of adultery.