A keystone is the wedge-shaped piece at the highest part of
an arch that locks the other pieces in place. The "other
pieces" are Steps One, Two, and Four through Twelve. In one
sense this sounds like Step Three is the most important Step,
that the other eleven depend on the third for support.
In reality however, Step Three is just one of twelve.
It is the keystone, but without eleven other stones to build
the base and arms, keystone or not, there will be no arch.
Through daily working of all Twelve Steps, I find that triumphant
arch waiting for me to pass through to another day of freedom.