In the Biblical account of spiritual creation (see Gen., chap. 1) the firmament appears. We can find its inspired meaning in Science and Health by Mrs. Eddy. In the chapter entitled "Genesis" she writes, "Spiritual understanding, by which human conception, material sense, is separated from Truth, is the firmament." And further down the same page, "Understanding is the line of demarcation between the real and unreal." Science and Health, p. 505.
The firmament, spiritual understanding, reveals God's standard of perfection for His creation, now and always. The universe and man are the totally good ideas of the one Mind, God. God being infinite good, He could never create or cause evil. His supreme love and wisdom allow no amalgamation of good and evil, the spiritual and material. Any apparent mixture in our experience can be no more than an illusion presented to human thinking by the darkness of material sense, which must be proved ultimately unreal.
We read in the Bible, "Doth a fountain send forth at the same place sweet water and bitter?" James 3:11. What a joy it is to realize that, truly, intelligence is spiritual and forever divided from ignorant material sense; substance being spiritual, it is forever separated from disease and decay; existence is eternal and forever divided from finiteness.