Writing a diary is a perilous business ; however careful or however conscious the diarist may be, posterity usually estimates him at a value very different from that which he puts on himself. The ingenuous diarist, of course, of whom Pepys is the prime example, reveals with complete candour both what he thinks he is and what he really is; but the conscious apologist is often nearly as naive. Mr. Guy Pocock , who is well known as a litterateur, will discuss some famous diarists in his talk this afternoon.