|“||In the box is the key to every object, scroll, spell ever collected for thousands of years under one roof. It is the supernatural mother lode.||”|
This key allowed access to the headquarters of the Men of Letters. It was described as the key to "every object, scroll, spell ever collected for thousands of years under one roof", as well as being the "supernatural mother lode".
The key is kept inside a small box with the Aquarian Star inscribed on it. It was small enough to be carried by Men of Letters and to be concealed from sight.
On August 12, 1958, the key was held by Larry Ganem, who passed it on to Henry Winchester for protection from the demon Abaddon. Henry Winchester traveled to the future with the intention of meeting his blood relative and son, John Winchester but ended up in Sam and Dean's motel room in 2013.
Unfortunately, Abaddon managed to follow Henry into the future. The Winchesters attempted to keep the demon from acquiring the key. They were successful, although the confrontation resulted into the death of Henry, the last surviving American Man of Letters, and the temporarily incapacitated the Knight of Hell.