I am both happy and honoured to have been asked to give this lecture on mysticism in memory of Leo Robertson, of whom I have many very pleasant memories. It was a delight to be wafted off to the Saville Club after a lecture here, and to discuss mysticism and philosophy on one of its many sofas. I am very sorry that this particular pleasure will not recur. Leo Robertson belonged to an old-fashioned climate of thought in which an interest in mysticism was respectable, and a long stay in the East had confirmed him in these leanings. I myself have always been constitutionally mystical, feeling that certain kinds of rapture, concerned with work, beauty, love and a few other things, are the only things absolutely worth having. I dropped my mysticism for a long period, partly on account of certain disillusioning experiences in my ’twenties, and partly out of deference to the dry methods and doctrine that prevailed in British philosophy. Latterly, however, increasing age has restored many of my illusions and made me generally more tender-minded; also, seeing the completely nugatory accomplishments of purely unmystical analysis, I have found myself reverting increasingly to my original mysticism. It was very refreshing to talk to a philosopher like Leo Robertson who took mysticism with the complete seriousness I think it deserves—as one of the truly fundamental human attitudes—but who also thought of it as supplementing and completing, rather than as undermining and nullifying, what other less rarefied thinkers do. It was also refreshing to hear all his talk about an earlier Cambridge, where he knew Wittgenstein in the full brilliance of his personal beauty as well as of his intelligence, and also knew Moore in the golden period of his dialectic, before he became so very preoccupied with the minutiae of the English language. Leo Robertson was a complete and rounded philosopher rather than a hamstrung one, and knowing him has been a factor in strengthening my resolve to be a complete and rounded thinker too.