“The key to the house of David on his shoulder”
I will place on his shoulder the key to the house of David. What he opens no one can shut, and what he shuts no one can open. (Isaiah 22:22 BSB)
What it sounds like today
An oddly specific image of a key carried on someone's shoulder.
The cultural key
The picture is an installation to high office. In a great house, the steward who controlled entry held the key, and ancient keys were not small metal objects but large wooden bars or L-shaped rods used to slide the door-bolt, big enough to be slung over the shoulder. To carry the key on the shoulder was to wear the visible emblem of the steward's authority: he alone decided who was admitted to the king and who was shut out, hence 'what he opens no one can shut.' So the verse announces a new palace administrator, Eliakim, being given full authority over the royal household of David. The image of the key of David borne on the shoulder, with the power to open and shut, is taken up in Revelation 3:7 for Christ's absolute authority. Read literally it is a curious detail; read as custom it is a ceremony of appointment.
Recovered meaning
The steward's key was a large wooden bolt-key carried on the shoulder as the badge of office over the royal household; laying it on Eliakim's shoulder installs him as chief steward with sole power to admit or exclude. It is an appointment ceremony, echoed in Revelation for Christ.