The Ecstatic Journey

...nature, the Earth would have more closely or more justly claimed for itself this nomenclature of the firmament The word "firmament" comes from the Latin "firmamentum," implying something solid or strengthening. The author argues that if the word literally meant "solid," it would apply better to Earth than the sky.; but because the nature of those things which are above us and sublime is very thin and rare, and cannot be perceived by any sense, Moses Traditionally regarded as the author of Genesis. called this the firmament: in comparison to those bodies which are very thin, and which are easily perceived by the senses. St. Basil, Homily 1. And a little later: “Certain people,” he says, “having rejected and set aside this opinion (that the heaven consists of the four elements) as if it were improbable, have introduced by their own ingenuity a fifth essence Also known as "quintessence" or "aether," this was Aristotle's theory that the heavens were made of a unique, incorruptible substance different from Earth's fire, air, water, and earth. of body for the composition of the heaven, a fictitious thing devised for the occasion; therefore, because of these logical necessities, having rejected the reasoning of their ancestors, they needed to support their opinion by a certain private and peculiar supposition—those who supposed a fifth essence of body for the generation and constitution of the heavens and stars.” And a little later: “If we now proceed to speak about these matters, we shall fall into trifles just as they did; therefore, letting those things go, so that they may strike each other down in their mutual sword-fights of controversy, and likewise setting aside the talk of a fifth essence, let us have faith in Moses.” St. Basil calls the fifth essence of the heavens "trifles." To this, the third light of the Holy Church, Saint Ambrosius Saint Ambrose (c. 340–397), a Bishop of Milan and influential theologian., subscribes in his Hexameron A commentary on the six days of creation described in Genesis.:

St. Ambrose, in his Hexameron, asserts the fluid substance of the heaven. “From the elements,” he says, “all these things which are in the world are generated. Now there are four elements: air, fire, water, and earth, which are mutually mixed in all things.” And later: “Regarding the quality and substance of the heaven, it is enough to set down those things which we find in the writings of Isaiah, who expressed the quality of the celestial nature in modest and common words, saying: that He established the heaven like smoke A reference to Isaiah 51:6: "the heavens shall vanish away like smoke."—wishing to declare its subtle nature, not a solid one.” To all of which Saint Epi-