Rather more than twenty years ago, on a spring morning of alternate cloud and sunshine, I acted as guide to Johan Huizinga, the author of this book, when he was on a visit to Oxford. As it was not his first stay in the city, and he knew the principal buildings already, we looked at some of the less famous. Even with a man who was well known all over the world as a writer, I expected that these two or three hours would be much like the others I had spent in the same capacity with other visitors; but this proved to be a day to remember. He understood the purposes of these ancient buildings, the intentions of their founders and builders; but that was to be expected from an historian who had written upon the history of universities and learning. What surprised and delighted me was his seeing eye. He told me which of the decorative motifs on the Tower of the Four Orders were usual at the time when it was built, and which were less common. At All Souls he pointed out the seldom appreciated merits of Hawksmoor's twin towers. His eye was not merely informed but sensitive. I remembered that I had heard of his talent for drawing, and as we walked and talked I felt the influence of a strong, quiet personality deep down in which an artist's perceptiveness was fused with a determination to search for historical truth.