The April 2013 issue of The Way journal (the journal of the British Jesuits) featured an article by Harvey D. Egan titled: The Mystical Theology of Karl Rahner. Egan bases it on a longer treatment in chapter 3 of a book I’m reading at present Karl Rahner: Mystic of Everyday Life.
Here’s an excerpt from the journal article
“…Rahner offers common human experiences to help us ‘dig ... out from under the rubbish of everyday experience’ real life occurrences of grace, such as accepting with hope the experience of utter loneliness; forgiving with no expectation of the other’s gratitude or even of feeling good about one’s selflessness; being utterly faithful to the depths of one’s conscience, even when taken as a fool; praying, even when it feels useless; maintaining faith, hope and love, even when there are no apparent reasons for so doing; experiencing bitterly the great gulf between what we desire from life and what it actually gives us; and silently hoping in the face of death. God is experienced, in Rahner’s view, most clearly and intensely... where the graspable contours of our everyday realities break and dissolve; where failures of such realities are experienced; when lights which illuminate the tiny islands of our everyday life go out…”
You can read the complete article (PDF) here.