Definition of Metaphor
Almost as soon as Watson meets Mary Morstan in Chapter 2, he begins to fall in love with her. This causes considerable tension for Watson, as the emotional effect of Mary's presence is a confusing counterpoint to Holmes's relentless, logic-driven detective work. Watson uses a metaphor to describe this tension:
So I sat and mused until such dangerous thoughts came into my head that I hurried away to my desk and plunged furiously into the latest treatise upon pathology. What was I, an army surgeon with a weak leg and a weaker banking account, that I should dare to think of such things? She was a unit, a factor—nothing more. If my future were black, it was better surely to face it like a man than to attempt to brighten it by mere will-o'-the-wisps of the imagination.
Adhering to the conventions of the Victorian Gothic, Doyle describes the city of London as a dark, forbidding place. In Chapter 3, he describes London's urban sprawl in the metaphorical language of some vast, tentacled monster:
Unlock with LitCharts A+We had indeed reached a questionable and forbidding neighbourhood. Long lines of dull brick houses were only relieved by the coarse glare and tawdry brilliancy of public-houses at the corner. Then came rows of two-storeyed villas, each with a fronting of miniature garden, and then again interminable lines of new, staring brick buildings—the monster tentacles which the giant city was throwing out into the country.
The Sign of the Four is the product of colonialism in more ways than one. The narrative revolves around the theft of a vast treasure trove from India, which was under Britain's colonial rule at the time, and Doyle's descriptions of some of his characters are also marked by racist, colonized attitudes toward people of color. In his descriptions of Tonga, in Chapter 10, Doyle relies on metaphorical language of inhumanity and animal rage:
Unlock with LitCharts A+Never have I seen features so deeply marked with all bestiality and cruelty. Hs small eyes glowed and burned with a sombre light, and his thick lips were writhed back from his teeth, which grinned and chattered at us with half animal fury. [...]
I can see the two of them now as they stood, the white man with his legs far apart, shrieking out curses, and the unhallowed dwarf with his hideous face, and his strong yellow teeth gnashing at us in the light of our lantern.