"When we say that order is transcendent, we mean to say that somehow, the order makes contact with some other reality, or some other 'something,' which lies outside of and beyond our normal experience. We need a word for this something. It is hard to find a suitable word, since, by definition, the something is beyond normal experience - and presumably, therefore, outside the range of things which have ordinary names... I use the word 'ground' to refer to this something.
The ground is imagined to be a pure reality. It is a state of reality, or substance, which is in the universe, but not accessible to normal perception and normal awareness. It is, however, not assumed to be distant. It is generally assumed to be here where we are, and even more real, more authentic, than the reality we normally experience. It is thus supposed to be a state of matter, or state of things, or state of existence, which is more fundamental - and of which one might say that 'the universe is really made of this stuff.' All this is 'the ground.' It is the ground beneath our feet, the ultimate ground of substance on which all things stand.
Color not only establishes wholeness as a single quality, a oneness beyond structure.It begins to establish a connection with this ground. The inner light we experience in the cases of great color seems to penetrate beyond normal experience, reaching through to this ground, showing us this ground, making us feel the ground... the experience of inner light reveals an ultimate world of existence as it really is, perhaps, and shows us a glimpse of a reality which is more profound, more beautiful, than the one we experience every day...[it is the] first direct experience of the I."
The Nature of Order, Book 4: