Taking, then, as the basis of our study, the three long stories, The Sign of Four, A Study in Scarlet, and The Hound of the Baskervilles, together with the twenty-three short stories, twelve in the Adventures, and eleven in the Memoirs, we may proceed to examine the construction and the literary antecedents of this form of art. The actual scheme of each should consist, according to the German scholar, Ratzegger, followed by most of his successors, of eleven distinct parts; the order of them may in some cases be changed about, and more or less of them may appear as the story is closer to or further from the ideal type. Only A Study in Scarlet exhibits all of the eleven; The Sign of Four and ‘Silver Blaze’ have ten, the ‘Boscombe Valley Mystery’ and the ‘Beryl Coronet’ nine, the Hound of the Baskervilles, the ‘Speckled Band’, the ‘Reigate Squires’, and the ‘Naval Treaty’ Eight, and so on till we reach ‘the Five Orange pips’, the ‘Crooked Man’, and the ‘Final Problem’ with five, and the ‘Gloria Scott’ with only four.
The first part is the Proömion, a homely Baker Street scene, with invaluable personal touches, and sometimes a demonstration by the detective. Then follows the first explanation, or Exegesis kata ton diokonta, that is, the client’s statement of the case, followed by the Ichneusis, or personal investigation, often including the famous floor-walk on hands and knees. No. 1 is invariable, Nos. 2 and 3 almost always present. Nos. 4, 5 and 6 are less necessary: they include the Anaskeue, or refutation on its own merits of the official theory of Scotland Yard, the first Promenusis (exoterike) which gives a few stray hints to the police, which they never adopt, and the second Promenusis (esoterike), which adumbrates the true course of the investigation to Watson alone. This is sometimes wrong, as in the ‘Yellow Face’. No. 7 is the Exetasis, or further following up of the trial, including the cross-questioning of relatives, dependents, etc., of the corpse (if there is one), visits to the Record Office, and various investigations in an assumed character. No. 8 is the Anagnorisis, in which the criminal is caught or exposed. No. 9 the second Exegesis (kata ton pheugonta), that is to say the criminal’s confession, No. 10 the Metamenusis, in which Holmes describes what his clues were and how he followed them, and No. 11 the epilogos, sometimes comprised in a single sentence. This conclusion is, like the Proömion, invariable, and often contains a gnome or quotation from some standard author.
(Monsignor Ronald A. Knox. Studies in the Literature of Sherlock Holmes, 1911)