This time it’s been planned. Every detail. I am wanted. I have been chosen. They will build me to a template that someone has ordered. I am going to be a girl. Blond with blue eyes, a skin that tans easily to protect me from the sun, and a talent for playing the violin. Now that will be useful. I have always found an analogy with music useful in defining the laws ofmotion, in codifying the properties of colour. But none of it will have anything much to do with my parents. Heredity is a thing of the past. A matter of choice.

They may start with a scrap of their own DNA but everything else is bolted on, made to measure. I won’t be able to catch measles or TB. I’ll be immune from various kinds of cancer. I will be healthy as they can make me, optimistic in outlook and fond of small fluffy animals. I’ve been programmed to live for 150 years so let’s hope the optimism doesn’t run out. I thought I’d done well to make it to 84 last time. But from where did they order the intellect? Did I leave traces of myself on a manuscript or in a vial?

The difference is that this time I’ll remember. Remember my last incarnation. Remember who I was and what I was. Now that is something new. Usually you are born into a state of utter forgetfulness. Perhaps this comes with the package. Perhaps remembering is some kind of technical advance. Is this the philosopher’s stone? The key to eternal life? The secret ...