In what follows I shall reflect on some of the things Professor Lewis has said in various contexts on the theme of inter-religious understanding, but taking a cue mainly from remarks made in his recent book Jesus in the Faith of Christians. Our sights will be set on the extent to which understanding is possible and, going on from there, the extent to which a sharing of insights is possible. The theme suggests a certain progression within experience. There is by now a considerable literature on the subject. Some of it gives the impression of what, with due respect to one of the greatest poets of all time, might be called a kind of Rabbie Burns Prinzip in reverse. Would that we could understand the ‘other’ as we understand ourselves. This Prinzip runs into a problem right away, for how far does our self-understanding reach? Those familiar with the psycho-analyst's couch or even those unfamiliar with this particular discipline, for discipline it is, find it to be an endless process. How far, moreover, does our ‘understanding’ of our own faith and tradition extend? Is ‘understanding’ the right word anyway? To speak of entering more deeply into the Divine mystery, as the man of faith well may, is, ipso facto, to witness to the inadequacy and even irrelevancy of all categorial nets. The prayer to ‘Lighten our darkness’ is less a philosopher's plea for intelligibility than a cry for succour, that the clouds of doubt and unbelief may be, through Divine grace, in some way which we cannot understand, penetrated and dispelled.