What a joy and inspiration it is to realize that we are given dominion by God over every material condition and circumstance. The very first thing we learn concerning man, as recorded in the first chapter of Genesis, is that he is given dominion: "And God said, Let us make man in our image, after our likeness: and let them have dominion." When we understand this divine gift of dominion, it floodlights human consciousness with hope, strength, courage, conviction, and achievement. Spiritual dominion is an integral part of the consciousness of man. When the ego goes to God, we gain the spiritual certainty that evil is without power and is, figuratively speaking, put under our feet into the dust of nothingness.
Turning again to the first chapter of Genesis, we find another important fact recorded. This fact enables us to see by means of the faculty of reason why we have dominion and how to exercise it. The fact referred to is related in verse 7: "And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so." By means of the firmament God divides the elemental forms of error from the fundamental facts of Truth. In human experience good and evil often seem to commingle, but the firmament reveals the dividing line as distinct.
Mary Baker Eddy defines "firmament" in "Science and Health with Key to the Scriptures" as follows (p. 586): "Spiritual understanding; the scientific line of demarcation between Truth and error, between Spirit and so-called matter." And elsewhere she writes (ibid., p. 505), "Spiritual understanding, by which human conception, material sense, is separated from Truth, is the firmament." It is spiritual understanding which separates error from Truth, the tares from the wheat, the unreal from the real.
