Which stone in an arch holds all the other stones together?
In arch architecture, the stone that holds all the other stones together is the very top stone. It is set in a V shape and supports everything. This illustrates the chief cornerstone, which the builders rejected but which should have held the architecture together.
Les teaches that in arch architecture, the very top stone is the one that holds everything together. It is put in in a V, and it just supports everything. He connects this to the chief cornerstone, which Christ was to have been. According to the legend he recounts (not Scripture), the chief cornerstone was brought in ahead of time, but the engineers and architects could not recognize it, so they dumped it in a vacant lot where weeds grew around it. That stone should have been the chief cornerstone holding all the architecture together, yet it became the stone people bumped into in ignorance. This illustrates the rejected stone.