A revisiting of the Third Secret and what Pope Benedict XVI wrote about it at the time...From a Commentary by then Cardinal Ratzinger (now Pope Benedict XVI) on the Third Secret of Fatima:
And now they are told why they have been exposed to this moment: “in order to save souls”—to show the way to salvation. The words of the First Letter of Peter come to mind: “As the outcome of your faith you obtain the salvation of your souls” (1:9). To reach this goal, the way indicated —surprisingly for people from the Anglo-Saxon and German cultural world—is devotion to the Immaculate Heart of Mary. A brief comment may suffice to explain this. In biblical language, the “heart” indicates the centre of human life, the point where reason, will, temperament and sensitivity converge, where the person finds his unity and his interior orientation. According to Matthew 5:8, the “immaculate heart” is a heart which, with God's grace, has come to perfect interior unity and therefore “sees God”. To be “devoted” to the Immaculate Heart of Mary means therefore to embrace this attitude of heart, which makes the fiat—“your will be done”—the defining centre of one's whole life. It might be objected that we should not place a human being between ourselves and Christ. But then we remember that Paul did not hesitate to say to his communities: “imitate me” (1 Cor 4:16; Phil 3:17; 1 Th 1:6; 2 Th 3:7, 9). In the Apostle they could see concretely what it meant to follow Christ. But from whom might we better learn in every age than from the Mother of the Lord?