Theologising with a pure heart according to Joseph Ratzinger

McGregor, Peter John In his commentary on the first chapter of 'Gaudium et Spes', Joseph Ratzinger writes the following: '[The] organ by which God can be seen cannot be a non-historical "ratio naturalis" which just does not exist, but only the ratio pura, i.e. purificata or, as Augustine expresses it echoing the Gospel, 'the cor purum'. The question that this article addresses is: What does it mean to theologise with a cor purum? An answer to this question will be attempted via the work of Ratzinger. In order to arrive at an answer, three particular questions must be addressed: For Ratzinger, what is theology, what is the heart, and what is a pure heart?