The ancient magical conception of God places him in the scheme of the universe, and evil is the inevitable contrast that complement good. God permits the existence of the shadow so it may intensify the purity of the light. Indeed he has credited both and they are inseparable the one being necessary to and incomprehensible without the other.
The very idea of goodness loses its meaning if considered apart from that of evil--Gabriel is lost to Satan and Satan to Gabriel. The dual nature of the spiritual world penetrates into every department of material and spiritual life. It is typified in light and darkness, cold and heat, truth and error, in belief, the names of any two opposing forces will serve to illustrate the great primary law of nature, which is, the continual conflict between the positive, or good, and the negative, or evil.
Scripture illustrates this point in the story Cain and Abel. The moral superiority of his brother Abel is irksome to Cain, and finally intolerable. He murders Abel, thus bringing on his head the wrath of God and the self-punishment of the murderer. For in killing Abel Cain has done himself no good, but harm. He failed to do away with Abel's superiority, but has taken on himself the burden of guilt that can be expiated only by much suffering.
In the Scriptures suffering, which is exemplified many times, is shown to be the only means by which evil is overcome by good. Cain re-appears in the story of the prodigal son, who after privation and suffering is restored to the father who forgives him fully and freely.
The possibility of sin and error is therefore entirely consistent with and even inseparable from life, and the great sinner a more vital being than the colorless character, because having a greater capacity for evil he also has a greater capacity for good, and in proportion to his faults so will his virtues be when he turns to God. "There is more joy in heave over one sinner that repenteth than ninety and nine just persons," because more force of character, more power for good and evil is displayed by the sinner than by the feebly correct. And that power is the most precious thing to life.
This great dual law, right and wrong, two antagonistic forces, or whatever one wishes to call them, is designated as a duad. It is the secret of life and the revelation of that secret means death. This secret is embodied in the myth of the Tree of Knowledge in Genesis. Only at death will this discord be resolved, but not till then.
From the duad is derived the triad on which is based the Trinity. Two forces producing equilibrium, the secret of nature, are designated by the duad, and these Three, called life, good, evil, constitute one law. By adding the conception of unity to that of the triad one reaches the tetrad, the perfect number of four, the source of all numerical combinations. According to (Christian) theology there are three persons in God, and these three form one Deity. Three and one make four because unity is required to explain the Three. Hence, in almost all languages, the name of God consists of four letters. Again, two affirmations make two negations either possible or necessary. According to the Kabbalists the name of the Evil one consisted of the same four letters spelled backward, signifying that evil is merely the reflection or shadow of good. "The last reflection or imperfect mirage of light in shadow."
All which exists in light or darkness, good or evil, exists through the tetrad. The triad or trinity, then, is explained by the duad and resolved by the tetrad.