What is the origin of potted beef?

The earliest known reference to potted beef comes from the 17th century, with the publication of _The Accomplisht Cook_, by Robert May. The book provides instructions for making "Potted Beef". The recipe calls for lean beef, suet, salt, pepper, and nutmeg. The meat is boiled until tender and then mashed into a paste. The paste is then mixed with the other ingredients and placed in a pot. The pot is covered and sealed with a layer of suet. The potted beef is then cooked in a slow oven until it is thickened.