This world is a world of duality. None of the character of this world is free from this duality. The conversion of weather into hot and cold, the shadow of sorrow over happiness, or happiness over sadness, respect and a second later disgrace, health and disease, love and hatred, nightfall and daybreak, all these dualities are actually opposite aspects of the character of the world. In the world of duality as long as we fail to understand these opposites, it is difficult to understand anything. Every human, from birth to old age is a document of experience. If goodness permeates this document, then it is precious and beneficial. But if evil penetrates it from head to toe, then the document is ugly and frightful.