How is the simple to be achieved? A spiritual simplicity of heart

In my description of the fundamental process, I have stated that what happens next (at any moment in the unfolding of a living process) is the simplest thing that can be done to intensify existing centers. It is necessary that it must be simple because if there is too much extraneous clutter, the clutter gets in the way, makes less room for new necessary structure that the unfolding process is trying to achieve. Thus, “doing the simplest thing”, only the thing which is required and nothing beyond what is required, is a practical and efficient necessity.
What is going on here is more than procedural simplicity. It is also a visible simplicity. When an unfolding process has succeeded — when a living process has succeeded — we may always recognize its results by a visible simplicity in the geometry and character of what is produced.
The buildings which are most intensely living, most profound, are marked by an intense simplicity. This occurs because it is necessary to what they are and to what they have become during the process that gave them life.
Further, simplicity is also not merely a geometrical ideal, but an attained internal purity — something we grasp and experience as associated with a spiritual state.
Simplicity is a spiritually achieved state of art. Among great works of art in history, those of greatest depth have nearly always been simple. Their simplicity comes from the Ground; their spirituality lies in their simpleness of attitude.
From a human point of view, this simplicity is easy enough to understand. Since a humble attitude requires that what is created is a perfect and indivisible unity, it implies that complexity of structure must gradually melt away to pure simplicity.
Things cannot become deep until they reach a state of extreme purity that we might call purity of heart. This purity of heart cannot be attained unless a thing is pure — and therefore simple. All the extraneous stuff, whatever is not essential, must be removed. In this fashion, it is intuitively clear that only a very simple thing can be spiritual.

Reminds me of good movies: everything you see, everything that will receive your attention at any point during a movie, even if it is just a detail that looks irrelevant at that time, will have a purpose. Everything else is removed.

Using the language of Book 4, I may say:
Those objects whose order makes them capable of reaching to the Ground, giving us a glimpse of it, always seem to have simplicity. They seem to need simplicity to touch the Ground.
I can rephrase this spiritual dictum in other words.
Any good example of living structure always has a very high density of sustaining relations among its parts. These sustaining relations, which are always made, in some form, from the fifteen transformations, occupy a great deal of “space” — so much that there is usually not room for all of them in the relatively small extent of a physical object. However, there is room for all of them when they are extremely compressed, when their density is very great.
This kind of compression, in which the density of sustaining relations is very high, can only be attained in a thing when that thing is extremely simple.

In Book 1, I concentrated on the idea that the field of centers os complex. This was a necessary emphasis in the earlier chapters. In the 20th century we were living in an era when crude oversimplification of design existed widely, and the subtle complexity that is characteristic of wholeness was often lost. However the idea of living structure will be misunderstood of we do not now pass beyond complexity to reach simplicity.

Plan of St. Gall

Each element is drawn as simply as possible. […]
Almost all of them are shown as simple rectangles. The plan is thus composed of the very simplest symmetries. And yet, each one is exactly where it should be; and, amazingly, each part is unique according to its place.
The overall arrangement is extensive and intricate, but still perfectly simple-hearted. Each essential thing is given not one element of structure more than it requires. Complex shapes appear only when they come about naturally, from the interaction of the elements.
The author of the plan was too childish to add any extra structure; it would have seemed like showing off.
The process which produced this plan was certainly practical, but leavened by great simplicity of heart. It consisted — I believe — of taking every step in the sequence of structure-preserving transformations in the simplest way possible. When new centers could be made symmetrical, they were. When they had to be asymmetrical, they were made so. As the monk of the St. Gall plan followed this process in his drawing, he gradually got something which became more and more complex (in a comfortable, organic way) but was still gentle and simple in heart.

#book/The Nature of Order/2 The process of creating life/17 Simplicity#