"You were the eighth Horcrux, Harry, the Horcrux he never meant to make. He had rendered his soul so unstable that it broke apart when he committed those acts of unspeakable evil, the murder of your parents, the attempted killing of a child. But what escaped from that room was even less than he knew. He left more than his body behind. He left part of himself latched to you, the would-be victim who had survived." Dumbledore took a breath and continued "His knowledge remained woefully incomplete however... That which Voldemort does not value, he takes no trouble to comprehend. Fae and other creatures, Wandlore, Family, Voldemort knows and understands nothing.... That they all have a power beyond his own, a power beyond the reach of any magic, is a truth he has never grasped.... He took your blood believing it would strengthen him. He took into his body a tiny part of the enchantment your mother laid upon you when she died for you. His body keeps her sacrifice alive, and while that enchantment survives, so do you and so does Voldemort’s one last hope for himself. Without meaning to, as you now know, Lord Voldemort doubled the bond between you when he returned to a human form. If he could only have understood the precise and terrible power of that sacrifice, he would not, perhaps, have dared to touch your blood ..."Harry was a little surprised and confused