It was a little over ten years ago, 1967–8, that H. D. Lewis delivered the first series of Gifford lectures, The Elusive Mind, in the University of Edinburgh. It was my privilege that year to be an auditor in the Seminar at King's College that Professor Lewis was conducting with his students in the area of this topic. I had already read the works in which, in the midst of neo-orthodox and existentialist religious movements, he had devoted himself to critical valuation of those doctrines - witness his Morals and the New Theology (1947), and Morals and Revelation (1951). This earlier work prepared for a comprehensive interpretation of religious experience in his book in 1960: Our Experience of God.