Emergence of the arches
So far, we had beautiful openings in the long walls — doors and windows, these beautifully, gently, arched openings. But there was nothing yet of a similar character in the cross-walls. To make the space feel three-dimensional, whole, solid, and at one, a similar series of arched openings was needed — I felt — in all the cross-walls, something that would tie the walls together structurally, that would make openings in the cross-walls correctly.
It was only a small step from that thought to the thought that the very same arches, if introduced into a system of four walls, would provide a kind of cross-structural stability which would reinforce the action of the massive walls and ring beam.
We then began to examine each of these cross-walls, one by one. They told us rather simply what to do. All we needed was a kind of language which would allow any combination of arched openings to be created, and we could lay out all four cross-walls without difficulty.
This final touch (at a fairly massive scale), not foreseen or contemplated at the time of the initial drawings or even construction, is what now holds the building together most firmly, gives it a solid and definite unity as a thing.
As this unity came into being, so did the being nature of the centers themselves, individually, together, all at once. The thickness of the members feels profound. Windows are the right size, in the right positions. Alcoves are the right size. Ceilings are the right height. The coherence of the whole has no need to be wrong on these points. It is careful consideration of the feeling of these kinds of things which informs the whole and makes it sensible.