Deepness

The essential, foundational mythic-metaphysical Idea of early German Romanticism was the animist notion that Nature is ensouled (the 'World Soul').  It had the function of healing the split between Man and Nature by conflating the inner depth of the Person with the outer depth of the Cosmos, into a Whole.  This was a metaphysical belief of the philosophers, but, now as then, many do not experience Reality in this way or believe that it is true.  But it is a necessary fiction, that requires a state of suspension of disbelief, in which analogistic/symbolic thinking is accepted, such as occurs in dream or trance, so that one can believe in it, but also disbelieve when strict rationality is required.  This was a sophistication lost on the German philosophers, it seems. 
Ecology, both in its shallow and deep aspects, was the creation of 19th century German Romantic Idealist culture.  It is based on the perception/belief of the Oneness of Mind and Nature-- that is, in a World Soul or Nature-Mind, but specifically in a transhuman Mind of Nature (biospheric).  This unifying archetypal ecological Idea is the energizing creative basis for a 'New Mythology' (spoken of by the early German Romantics) necessary to interpret Reality so that a new ecological culture-civilization embedded in, one with, Living Nature can be formed.  It is a simple, coherent, viable, and powerful value-idea that will override those undergirding the old culture-civilization.  The presence of this transformative quality is what we call 'Deepness'.