In his introduction to Gregory's "History of the Franks", Ernest Brehaut analyzed the Romano-Christian concepts that gave relics such a powerful draw. He distinguished Gregory's constant usage of "sanctus" and "virtus", the first with its familiar meaning of "sacred" or "holy", and the second as "the mystic potency emanating from the person or thing that is sacred. ... In a practical way the second word " ... describes the uncanny, mysterious power emanating from the supernatural and affecting the natural. ... These points of contact and yielding are the miracles we continually hear of".