If we plant a seedling after first clearing away the rubbish from the ground, then it will grow fast and give good fruit when it becomes a young plant. Similarly, when we plant a new tree in the mind after first cleansing it, then it brings forth leaves and fruits quickly, becoming green and fresh. As you expel vicious materials from the body by the natural system, so thoughts, passions, exciting anger and density of passions also have to be expelled. Until the brain is cleansed from the density of passions and exciting anger, man cannot become human.