What is keystone in freemasonry

The keystone belongs properly to the Mark Master's Degree, whereas the central emblem of the Holy Royal Arch is the Stone of Foundation 1. Mackey emphasizes that the keystone functions primarily as the subject of a historical legend rather than as an isolated symbol 1. Unlike Craft degrees that use direct emblems—such as the trowel—to convey moral lessons, capitular Masonry imparts instruction through narrative traditions based on events in Masonic history 1.

In an allegorical reading of architectural stone-fixing mechanisms, Wilmshurst treats the dovetailed clamp used for lifting heavy weights as an emblem of the Divine Light grafted into the human organism 2. This spiritual integration enables a Mason to resolve insuperable difficulties and perceive all things in their true relation 2.