An excerpt from Livia Kohn's Living Authentically: Daoist Contributions To Modern Psychology:
"... as already the Daode jing says: "The Dao that can be told is not the eternal Dao" (ch. 1). This distinguishes an eternal aspect of Dao that is ineffable and beyond sensory perception from visible and tangible patterns that manifest in the rhythmic changes and natural processes of the world.
The first, the eternal Dao at the center of creation, although the ground and inherent power of human beings and the world, is entirely beyond ordinary perception. Vague and obscure, it is beyond all knowing and analysis; we cannot grasp it however hard we try. The human body, senses, and intellect are not equipped to deal with it. The only way a person can ever get in touch with it is by forgetting and transcending ordinary human faculties, by becoming subtler and finer and more potent, more like the Dao itself.
Dao at the periphery, on the other hand, is characterized as the give and take of various pairs of complementary opposites, as the natural ebb and flow of things as they rise and fall, come and go, grow and decline, emerge and die. Things always move in one direction or the other: up or down, toward lightness or heaviness, brightness or darkness. Nature is a continuous flow, described in terms of yin and yang as the alternation of complementary characteristics and directions that cannot exist without each other. This becoming can be rhythmic and circular, or it can move back toward the source of life in the ineffable Dao, which at the same time is a forward movement toward a new level of cosmic oneness."
Escher's hands illustrates this perfectly: the two hands in the painting representing the various pairs-of-opposites constituting the ten-thousnad-things of the phenomenal world ("Dao at the periphery"); with Escher-the-painter's hand (as the real and ultimate creator) the equivalent of "the Eternal Dao."
Or, in the language of Buddhism, the two hands of the painting represent emptiness/dependent-origination -- which give rise to all of the appearances of the relative world; with Escher-the-painter's hand the equivalent of Primordial Wisdom, Pure Awareness, Rang Rigpa (our innermost being).
In a new essay -- Taoism & Deep Mind, whose second page introduces Livia Kohn's book -- I explore "that which transpires behind that which appears," and in particular the typically unseen aspects of mind, which deeply condition what appears as the phenomenal world -- and oftentimes function as a veil which prevents the ten-thousand-things from continuously and transparently pointing back to their source in Tao.