In the most ancient Teachings, the manifested Trinity of Father, Mother, and Son was considered as an emanation of the highest, eternally hidden Cause; and the latter, in turn, as that of the Causeless Cause.
This Causeless Cause is the Parabrahman of the Hindus. However, Parabrahman is not a Personal God. He is ‘That’ of the Vedantists. Parabrahman is simply the Reality which has no equivalent - the Absolute, or rather, the infinite abstract Space, which contains the potential space, also called Aditi. (LHR I, p 487)
STANZA I. The Eternal Parent, wrapped in Her Ever-Invisible Robes, had slumbered once again for Seven Eternities "
The ‘Parent’, Space, is the eternal, everpresent Cause of all - the incomprehensible Deity, whose ‘Invisible Robes’ are the mystic Root of all Matter and of the Universe. Space is the one eternal thing that we can most easily imagine, immoveable in its abstraction and uninfluenced, by either the presence or absence in it of an Objective Universe. It is without dimension, in every sense, and self-existent. Spirit is the first differentiation from ‘THAT’, the Causeless Cause of both Spirit and Matter. As taught in the Esoteric Catechism, it is neither ‘limitless void’ nor ‘conditioned fullness’, but both. It was and ever will be. (SD I, p 35)
"What is it that ever is?" "Space, the eternal Anupadaka." "What is it that is ever coming and going?" "The Great Breath." "Then, there are three Eternals?" "No, the three are one. That which ever was is one, that which is ever being and becoming is also one: and this is Space." (SD I, p 11)
see also Space Within Space

This definition is in context to Classic Yoga. See more contextual defintions for Space.