Definition of Irony
In Chapter 1, Doyle wastes no time introducing the reader to Holmes's penchant for deductive reasoning and obsession with rational decision-making. Holmes himself describes how he reaches his confounding conclusions with characteristic self-confidence, which he conveys through the use of hyperbole. Additionally, the moment is an example of logos and situational irony:
'It is simplicity itself,' he remarked, chuckling at my surprise—'so absurdly simple that an explanation is superfluous; and yet it may serve to define the limits of observation and of deduction.
In Chapter 6, Holmes must contend with the incompetent Athelney Jones, a local policeman whose shoddy intuition about Bartholomew's murder hinders Holmes's own investigation into the crime. As Holmes disparages Jones to Watson (and the reader), he lets loose two literary allusions—one in French, one in German:
Unlock with LitCharts A+'He can find something,' remarked Holmes, shurgging his shoulders; 'he has occasional glimmerings of reason. Il n'y a pas des sots si incommodes que ceux qui on de l'esprit?'