Good never produces evil, nor evil, good. Jesus asked, "Do men gather grapes of thorns, or figs of thistles?" On page 370 of the Christian Science textbook, "Science and Health with Key to the Scriptures," Mrs. Eddy says: "The body improves under the same regimen which spiritualizes the thought; and if health is not made manifest under this regimen, this proves that fear is governing the body. This is the law of cause and effect, or like producing like."
We find the "law of cause and effect, or like producing like," in all activity. A rosebush produces roses, not apple blossoms; it is governed by "the law of cause and effect, or like producing like."
If "the body improves under the same regimen which spiritualizes the thought," then, in order to have a healthy and harmonious body, we need to spiritualize our thinking, to bring it into accord with Truth. And the arguments of mortal mind need to be discarded as unreal and powerless. Can anyone conceive of God, who is all-power, producing discord and unhappiness for His children? No; power belongs to God, and to God alone. The so-called law of mortal mind cannot hold us under a sense of fear, because it is not law at all, since God is the only lawmaker. And as we see that error is lawless, with nothing to support it, we are lifted above the fear of it.