Key to the Secret Door
The Key to the Secret Door is a small silver key with a long barrel and intricate wards, given by Gandalf to Thorin Oakenshield as part of the quest to reclaim the Lonely Mountain. It is the only means of opening the hidden entrance on the western side of the Mountain, a passage too small for the dragon Smaug to use, and its successful use at the precise moment of Durin's Day marks the turning point that allows the company to enter the dragon's lair.
Origin and Delivery
Gandalf produced the key during the unexpected party at Bag-End, handing it to Thorin with the words, "Here it is!" and instructing him to "Keep it safe!" The key was made of silver, with a long barrel and intricate wards, and Thorin immediately fastened it upon a fine chain that hung about his neck and under his jacket. The key accompanied the map of Thror, which Gandalf had received from Thorin's father Thrain, who had been a prisoner in the dungeons of the Necromancer and had forgotten almost everything except the map and the key. The wizard explained that the key was meant for a secret entrance marked on the map, a hidden passage to the Lower Halls that was "five feet high the door and three may walk abreast"—too small for Smaug to use, even when he was a young dragon.
The Search and the Moment of Opening
After the company arrived at the Lonely Mountain, they spent days searching the western slopes for the hidden door. Bilbo Baggins, using Thror's Map and the moon-letters read by Elrond, led the dwarves to a small grassy bay high on the mountain-side, where a smooth rock-face showed no sign of any entrance. They beat on it, thrust and pushed at it, and implored it to move, but nothing stirred. The key remained unused until the last day of autumn, when Bilbo noticed an old thrush knocking a snail against a grey stone. Understanding the sign, he called the dwarves, and as the setting sun broke through a cloud, a red ray of light fell on the rock-face. A flake of rock split from the wall and fell, revealing a hole about three feet from the ground. Thorin hurried up, drew the key from its chain, and put it to the hole. It fitted and turned with a snap. The door swung inward, and darkness flowed out like a vapour from the mountain-side.
Significance
The key is the physical embodiment of the secret knowledge that makes the dwarves' quest possible. Without it, the hidden door could not be opened, and the company would have been forced to attempt the Front Gate, which was guarded by Smaug and would have required a mighty warrior or hero. The key's successful use at the precise moment of Durin's Day—when the last moon of autumn and the sun are in the sky together—demonstrates the importance of timing and the fulfillment of ancient prophecies. The key also connects the present quest to the tragic history of Thorin's family, as it was passed down from Thror to Thrain and finally to Thorin, surviving the dragon's destruction and the imprisonment of Thorin's father. After the door is opened, the key is never used again; the door is later shattered by Smaug's fury, and the key becomes a relic of the successful entry into the Mountain.
