title in other novels, including One, Two, Buckle My Shoe, Hickory Dickory Dock, A Pocket Full of Rye, and Crooked House.Hercule Poirot mentions the celebrated case of Hawley Harvey Crippen as an example of a crime reinterpreted to satisfy the public enthusiasm for psychology.Romeo and Juliet is a theme among characters recalling the trial, starting with solicitor Caleb Jonathan reading Juliet's lines from the balcony scene: "If that thy bent of love...". Jonathan compares Juliet to the character of Elsa Greer, for their passion, recklessness, and lack of concern about other people. Coniine (in the story, specifically coniine hydrobromide, derived from poison hemlock) was indeed the poison with which Socrates took his own life, as described by Phaedo, and has indeed been used to treat whooping cough and asthma. The "poisons act" referred to is the Pharmacy and Poisons Act 1933, now superseded by the Poisons Act 1972. The painting that is hung upon the wall of Cecilia Williams' room, described as a "blind girl sitting on an orange," is by George Frederic Watts and is called "Hope." In it, a blind girl is featured with a harp which, though it has only one string left, she does not give up playing. The description is by Oswald Bastable, a character in the third book in the Bastable series by E. Nesbit, titled The New Treasure Seekers. The other identifiable prints are Dante and Beatrice, and Primavera by Botticelli. Amyas has two paintings in the Tate. Miss Williams remarks disparagingly that "So is one of Mr Epstein's statues," referring to American-born British sculptor Jacob Epstein. When Poirot approaches Meredith Blake, he introduces himself as a friend of Lady Mary Lytton-Gore, a character known from Three Act Tragedy. This case is later referred to by Poirot many years later, in Elephants Can Remember, published in 1972. "Take what you want and pay for it, says God" is referred to as an "old Spanish proverb" by Elsa. The same proverb is cited in Hercule Poirot's Christmas. The proverb is mentioned in South Riding (1936), by Winifred Holtby, and in Windfall's Eye (1929), by Edward Verrall Lucas. The "interesting tombs in the Fayum" refers to the Fayum Basin south of Cairo, famous for Fayum mummy portraits. Angela Warren refers to Shakespeare, and quotes John Milton's Comus: "Under the glassy, cool, translucent wave". In the UK version of the story Five Little Pigs, Poirot refers