20 - Life is based on the law of polarity Life is based on the law of polarity Spenta Mainyu, the Good Spirit, and Angra Mainyu, the Evil Spirit, are inveterate foes. With the advent of man upon earth, the warfare between them has begun. It will end in the defeat of the Evil Spirit, when human life upon earth will end. The Evil Spirit deranges what the Good Spirit has arranged, frustrates what he has willed, levels down what he has raised, breaks what he has constructed and destroys what he has created. Human nature, likewise is based on the law of contrast and conflict.
Irreconcilable opposites exist side by side in human nature.
Vohu Manah, the Good Mind, and Aka Manah, the Evil Mind, are the two principles poised against each other in man. Vohu Manah with his good thoughts and Aka Manah with his evil thoughts are wrestling within man. The clinging creeper of evil has wound itself around the tree of goodness and chokes its life. Struggle is the fundamental fact of man's life. Man is a human being and an animal, a civilized man and a savage, an angel and a demon in one.