Space is neither a “limitless void,” nor a “conditioned fulness,” but both: being, on the plane of absolute abstraction, the ever-incognizable Deity, which is void only to finite minds, but on that of mayavic perception, the Plenum, the absolute Container of all that is, whether manifested or unmanifested: it is, therefore, that ABSOLUTE ALL. ...  Space is called in the esoteric symbolism “the Seven-Skinned Eternal Mother-Father.”  It is composed from its undifferentiated to its differentiated surface of seven layers.  (1888, pp. 8-9)

SPACE, which, in their ignorance and iconoclastic tendency to destroy every philosophic idea of old, the modern wiseacres have proclaimed “an abstract idea” and a void, is, in reality, the container and the body of the Universe with its seven principles.  It is a body of limitless extent, whose PRINCIPLES, in Occult phraseology–each being in its turn a septenary–manifest in our phenomenal world only the grossest fabric of their sub-divisions. ... the Kabalistic teachings (show) this idea, e.g., the seven-headed Serpent of Space, called “the great Sea.”   (p. 342)

     Blavatsky’s major criticism of the science of her day concerned the prevalent views of “space.”  Materialist scientists rejected the idea of Space as a substantive element, but considered it as simply a “void.”   This void was nothing and empty, non-substantive.  Space was a passive background within which three dimensional atoms move about interacting only through local effects and external relationships.  In contrast, Blavatsky’s “SPACE” refers to the “real SPACE” of the “Eternal Parent Space,” rather than the three dimensional space of manifest phenomenal existence.  This SPACE is described as a living Unity, simultaneously an apparent Void to the finite mind or physical perception, but also the Divine Plenum, container of all, to the mystically awakened.
     This SPACE is the ultimate AETHER–the root principle of all manifestation within both the spiritual and material worlds.   Whereas scientists of her day were arguing about the reality of the “ether,” before dismissing the concept in the early part of the twentieth century, Blavatsky never wavered in her insistence of the primacy of the Aether.  This Aether is  the container and foundation for all the laws of nature and all cosmic manifestations–and is the Eternal Parent Space itself.   This concept of the Aether is dramatically different from the ether being proposed in her day by the scientists, although it is perfectly compatible with the most  recent scientific concepts.  Of course, no-one in Blavatsky’s day had any conception of the sevenfoldness of this ultimate Aether:
 

The whole range of physical phenomena proceed from the Primary of Aether–Akasa. ... Modern science may divide its hypothetically conceived ether in as many ways as it likes; the real Aether of Space will remain as it is throughout.  It has its seven principles, as all the rest of Nature had, and where there was no Ether there would be no sound, as it is the vibrating sound-board in nature in all of its seven differentiations.  This is the first mystery the Initiates of old have learned.  (p. 536)

The Eternal Parent Space, the ultimate Aether, has seven skins, an inherent nature even within the Divine Essence.  This is  why, when creation occurs, the “first born” are seven Spiritual Intelligence, the seven Luminous Sons, and these create seven dimensional spiritual worlds and seven dimensional material worlds.   Everything is sevenfold since this septenary nature is latent in the Divine Essence even before the initiation of the creative forces.  It is a pattern of being, of existence, pre-existent in Non-Being!  Cosmic manifestation entails the unfolding of this inherent sevenfold nature within spiritual and material realms of creation.
     Understanding this enigmatic doctrine is a key to understanding the mysteries of cosmology, physics and metaphysics–both modern and ancient.  Blavatsky’s explanations of the Seven Skinned Eternal Parent Space is a remarkable and profound teaching of the ancient wisdom religions.  She writes: “Everything in the metaphysical as in the physical Universe is septenary.” (p. 158)  The opening Stanzas of Dzyan thus refer to the Seven Eternities, the Seven Ways to Bliss, the Seven Sublime Lords and the Seven Truths, and the Seven to be born from the Web of Light.
     In terms of the theological triunity, SPACE is the feminine principle–the Mother principle, which is also the root for matter.  It is equated with “the Great Sea” and with the “Chaos,” and with the “Deep.”  In the book of Genesis, before the beginning, “Darkness was upon the face of the deep.  And the Spirit of God moved upon the face of the waters.”  The terns “the deep” and “the waters” refer to the SPACE, the ultimate Aether of the Eternal Parent Space:

“The Great Water (the Deep or Chaos) is said to be seven cubits deep” –cubits standing here of course for divisions, zones, and principles.  Therein, “in the great mother, all the Gods, and the seven great ones are born.”  (p. 674)

The primordial nothingness–the void/plenum, in its nature as the Eternal Parent Space, has a seven fold nature.  This is the ultimate Aether or root principle for all cosmic manifestations.  This is an awesome and profound teaching of the archaic wisdom traditions–which anticipates the most startling and revolutionary ideas emerging within science in this twenty first century.

According to esoteric teaching there are seven primary and seven secondary “creations;” the former being the Forces self-evolving from the one causeless FORCE; the latter, showing the manifested Universe emanating from the already differentiated divine elements. ... Occult Philosophy ... never uses the term “creation,” nor even that of “evolution,” “with regard to primary ‘Creation’; but calls all such forces “the aspects of the Causeless Force.”  (p. 446) ...  Primary Creation is called the Creation of Light (Spirit); and the Secondary–that of Darkness (matter). ...  Both are found in Genesis ... . The first is the emanation of the self-born gods (Elohim); the second of physical matter.  (p. 450)