There is a "nuqta-i suwayda" (black dot) in the human heart. As the rebellion of any soul increases, the blackness of that dot within the spirit also grows until it finally becomes completely pitch black. The doors of divine grace are then closed. For the spirit has two sides: one facing the realm of the unseen and the other facing the visible world. Every effusion that reaches the spirit from the Almighty is transmitted by the spirit to the heart, which then distributes this grace to the other limbs, manifesting as actions and deeds appropriate to that grace. If the spirit darkens entirely, the door to the place where this grace should arrive is shut. The purification of this spirit from darkness is achieved only through faith. Indeed, as Imam Ali (may Allah be pleased with him) stated: Faith begins as a pure white dot in the heart, and as faith increases, that portion grows and expands. As faith further intensifies, this part of the heart becomes fully manifest and visible; as the veil is lifted and disappears, spiritual and metaphysical observations begin to appear in the heart.