Stone....

Stone arches are built using distinctive, wedge-shaped blocks known as "voussoirs," a French term derived from the Latin word for vault. Each of these were hewn and angled to fit together forming the traditional arc or vault. However, as each of these voussoirs are symmetrically fitted together, anyone who has studied geometry knows that the sum of those angles needs to be offset by one crucially cut piece to hold them all together. This key piece is known as the "keystone" or "cornerstone." 

In today’s epistle lesson, St. Peter quotes from the prophecy of Isaiah, “Behold, I am laying in Zion a stone, a cornerstone chosen and precious" (Isaiah 8:14), and again from the Psalms, "The stone which the builders rejected has become the head of the corner. This is the Lord's doing and it is marvelous in our eyes" (Psalm 118:22-23). Thus, He reminds us that Christ is this precious Keystone which holds His entire Church together. As St. Paul wrote, “He is before all things, and in Him all things hold together” (Col. 1:17)

Fr. John