The cornerstone is also of crucial importance to a building. It is itself part of and essential to the foundation; it helps to hold the building steady, and it also sets it and keeps it in line. The temple in Jerusalem had massive cornerstones. Armitage Robinson mentions one ancient monolith excavated from the southern wall of the temple which measured 38 feet 9 inches in length. The chief cornerstone of the new temple is Christ Jesus himself. Elsewhere he is also the foundation stone. But here Paul has particularly in mind the function of Jesus Christ in holding the growing temple together as a unity, For he is the chief cornerstone, in whom the whole structure is joined together and grows…The unity and growth of the church are coupled, and Jesus Christ is the secret of both. Since the “in Christ” concept is of an organic union, the most natural metaphors to illustrate it are organic metaphors such as the branches ‘in’ the vine and the members ‘in’ the body. Here the concept is transferred to construction work. As a building depends for both its cohesion and its development on being tied securely to its cornerstone, so Christ the cornerstone is indispensable to the church’s unity and growth. Unless it is constantly and securely related to Christ, the church’s unity will disintegrate and its growth either stop or run wild. — John Stott, The Message of Ephesians