The catechism calls mary the perfect embodiment of faith. why is this a fitting way to describe her?

It is then we must turn to the witnesses of faith: to Abraham, who "in hope. . . believed against hope";51 to the Virgin Mary, who, in "her pilgrimage of faith", walked into the "night of faith"52 in sharing the darkness of her son's suffering and death; and to so many others: "Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with perseverance the race that is set before us, looking to Jesus the pioneer and perfecter of our faith."53