In his teachings ‘Abdu’l-Bahá often highlighted the duality of human nature in order to encourage self-awareness and spiritual development.
In man there are two natures; his spiritual or higher nature and his material or lower nature. In one he approaches God, in the other he lives for the world alone. Signs of both these natures are to be found in men. In his material aspect he expresses untruth, cruelty and injustice; all these are the outcome of his lower nature. The attributes of his Divine nature are shown forth in love, mercy, kindness, truth and justice, one and all being expressions of his higher nature. Every good habit, every noble quality belongs to man’s spiritual nature, whereas all his imperfections and sinful actions are born of his material nature. If a man’s Divine nature dominates his human nature, we have a saint. Man has the power both to do good and to do evil; if his power for good predominates and his inclinations to do wrong are conquered, then man in truth may be called a saint. But if, on the contrary, he rejects the things of God and allows his evil passions to conquer him, then he is no better than a mere animal.