10th December, 18—

The date 10th December, 18—, is the date on which Henry Jekyll wrote the desperate, registered letter to Dr. Hastie Lanyon that set in motion the final chain of events leading to Lanyon's death and the revelation of Jekyll's secret. This single date anchors the epistolary climax of the novel, marking the moment when Jekyll, having involuntarily transformed into Edward Hyde in Regent's Park, was forced to appeal to his estranged colleague for the drugs that could restore his original form.

The Letter and Its Context

The letter, dated 10th December, 18—, was addressed to Lanyon and sent by registered post. Jekyll, writing as himself, appealed to their old friendship, stating that his life, honour, and reason were all at Lanyon's mercy. He instructed Lanyon to go immediately to Jekyll's house, force open the cabinet door with the help of Poole and a locksmith, and retrieve a specific drawer from a glazed press marked "E." The drawer contained powders, a phial, and a paper book. Jekyll then asked Lanyon to receive a man who would present himself in Jekyll's name at midnight and to hand over the drawer. The letter concluded with a postscript expressing the fear that the post might fail and that if the night passed without event, Lanyon would know he had seen the last of Henry Jekyll.

Lanyon's Response and the Consequences

Upon reading the letter, Lanyon was convinced his colleague was insane but felt bound to comply. He drove to Jekyll's house, where Poole had already summoned a locksmith and a carpenter. After two hours of work, the door was forced open, and Lanyon retrieved the drawer, returning with it to his home in Cavendish Square. At midnight, a small, deformed man—Edward Hyde—arrived. Lanyon, revolted by Hyde's appearance and manner, gave him the drawer. Hyde then mixed a potion from the contents and drank it, transforming before Lanyon's eyes into Henry Jekyll. The shock of witnessing this supernatural metamorphosis destroyed Lanyon's health; he took to his bed a week later and died within a fortnight, leaving behind a sealed narrative for Mr. Utterson to be opened only upon Jekyll's death or disappearance.

Narrative and Thematic Significance

The date 10th December, 18—, functions as a pivotal temporal marker in the novel's epistolary structure. It is the first date given in the final two chapters, which consist entirely of written documents: Lanyon's narrative and Jekyll's full statement. The letter written on this date is the catalyst for Lanyon's fatal knowledge, and its registered, formal nature underscores the extremity of Jekyll's desperation. The date also highlights the compression of time in the novel's climax: the events of that single night—the letter, the forced entry, the midnight visit, and the transformation—lead directly to Lanyon's death and, within weeks, to Hyde's suicide and Jekyll's final disappearance. The 10th of December thus stands as the moment when the secret could no longer be contained, and the epistolary form itself becomes the vehicle for the story's final, devastating revelations.