An allegory is a work of art in which characters and events take on metaphorical or symbolic meanings that are deliberately cultivated by the artist. The most famous literary allegory in English is John Bunyan's Pilgrim's Progress (1678), where symbolic characters (with names such as Christian, Evangelist, and Faithful) move through a symbolic plot (part of which, for example, involves their fleeing the City of Destruction) to arrive at the Celestial City eventually. Bunyan's allegory is clear and straightforward: Any person who wishes to reach Heaven must remain pure despite all of the hardships and tests he will face. Another widely known allegory is Edmund Spenser's The Faerie Queen (1590) in which different knights represent different virtues, such as holiness, temperance, and chastity. Because of their accessibility and moral teachings, allegories have been popular with readers since the beginnings of English literature.
While "The Secret Sharer" may not seem as obviously allegorical as the aforementioned works, it can nonetheless be read as an allegorical examination of a timid man becoming more daring and therefore, more complete. The primary allegorical element in the story is its plot: As the Captain journeys through the Gulf of Siam and eventually to within the shadow of Koh-ring, he also undertakes a metaphorical journey within himself. Just as a traveler is in a different place literally at the end of a journey, so the Captain is in a different emotional "place" as he watches Leggatt swim to shore.
Conrad's depiction of the Captain also invites the reader to consider the story's other allegorical implications. For example, the young and inexperienced Captain wants to behave in a resolute and forthright manner, but he lacks the courage and sense of command that would enable him to do so. Conrad's making the Captain the newly appointed commander of a ship on foreign seas evokes those situations in every person's life when he or she is called upon to show courage and steadfastness, but feels out of place and uncomfortable with such demands.
Leggatt's appearance changes all this. In terms of the allegory, Leggatt is like the scorpion that smuggled its sway into the Chief Mate's inkwell: sly, inexplicable, and potentially deadly. The fact that Leggatt killed a man — however accidentally or unintentionally — suggests his symbolic position as the more brutal, impulsive part of the human psyche. His initial nudity suggests his symbolically elemental essence in all of us: He is naked because he represents the human soul "stripped down" to its essentials without being "disguised" in any guise. When the Captain offers Leggatt one of his sleeping suits, the allegorical implications are unmistakable: Leggatt is — symbolically — a part of the Captain that readers see at the end of his "voyage."
Another piece of clothing that holds allegorical significance is the Captain's hat, which he gives to Leggatt before allowing him to escape the ship and swim to Koh-ring's shores. The last third of the story, when the Captain maneuvers the ship next to Koh-ring, repeatedly depicts the island as a symbol of death, looming over the Captain and his (understandably) terrified crew. However, to grow as a person (so Conrad's allegory goes), the Captain must experience a "brush with death" to test his newfound confidence. If not for Leggatt's losing the Captain's hat, which the Captain then uses to help him steer clear of the shoals, the ship would certainly be destroyed. This clarifies the plot. But in terms of the allegory, the hat suggests something else: Despite his having been assisted by Leggatt in finding his confidence and bravery, ultimately, the Captain himself is responsible for his transformation — a proposition that accords with the notion of Leggatt symbolically representing a part of the Captain's personality. Thus, the Captain's own hat saves his ship because it is the Captain himself who grows as a person and is responsible for his own change.
The Skipper of the Sephora enters the allegorical equation as well. As Leggatt symbolically represents the more passionate and dangerous side of man, the Skipper represents a side even more timid than the Captain at the beginning of the story. For example, he refuses to take a stand to help Leggatt, despite that the man Leggatt killed was an insolent sailor who could have cost all the men their lives and despite the fact that Leggatt killed the man accidentally. Thus, Conrad begins "The Secret Sharer" with the Captain being offered two extreme modes of behavior: Leggatt's and the Skipper's. The Captain encounters each one physically and emotionally, but by the end of the story, he has completed his allegorical journey through the symbolic shadow of death and looks forward, as does his symbolic counterpart, to a "new destiny."
Finally, the story's title reflects its overall allegory of growth and change. The Captain conceals Leggatt because — like many people — he tries to stifle and keep down the more physical and dangerous part of himself. He would rather possess a façade of cool control than fall prey to his own violent impulses. However, the story suggests that there are times in a person's life when he must call upon his "Leggatt" side to complete a dangerous task or prove himself worthy of his hire. We are all "secret sharers" of our darker selves, but we all keep them in reserve for use in dire situations.