The philosophy of ships being the question : if a ship has its planking replaced plank by plank over a period of years, when does it become a new ship? Yoachim applies this to humanity – once we have ultimate control of the biological self, and can engage and share/merge with others in virtual space, what is it that is the essence of humanity.
The story follows a fatal ski-ing trip on Earth by two advanced humans – or, at least, fatal to the corporeal existence of the native Earthwoman who has the misfortune to get in the way of the skiers. We follow the process of saving the victim through several perspectives and shared perspectives. And in the denouement, a fairly major application of the central conundrum is asked.