For the student of the Solar Sciences, many insights are to be gained from ancient allegories. The Supreme First Cause is seen in the 3-D physical plane as our Sun. The ancient Greeks taught that it has a counterpart, unobserved by the five human physical senses, which they called the Sun-behind-the-sun.

In olden times the name Empyrean was used as a name for the firmament, and in Christian literature, notably the Divine Comedy, for the dwelling-place of God, the Blessed, and celestial beings so divine they are made of pure light, and the source of all Light and creation. Empyrean, from the Medieval Latin empyreus, an adaptation of the Ancient Greek ἔμπυρος empyrus "in or on the fire (pyr)", properly Empyrean Heaven, is the place in the highest heaven, which in ancient cosmologies was said to be occupied by the element of fire (or aether in Aristotle's natural philosophy)[i].

Applying the mystical maxim, ‘As Above, So below,’ we know we have a Solar Heart within each of us. Our egoic sense of self is just a reflection of that central source of light.
 
REFERENCE FOOTNOTES:
[i] https://en.wikipedia.org/wiki/Empyrean