Few medical procedures are neccessary to maintain an occupancy once it is established. A bucket of disinfectant every two days, one or two injections of penicillin. The wiring, the other technical procedures, even the selection of the original subject all seem to have a preservative effect. What is meant by this ? Well, not simply that the more durable guests are chosen. In fact the reverse can be said: being chosen actually confers a quality of spiritual endurance the guest may not have possessed in ordinary life. Of course a certain physical toughness is also necessary, and guests can often surprise in that respect. Some won’t survive the first two or three days; those I always recognise, and dispose of quickly. But others seem so frail and last so long.