Yarlen Zey observed the computer's plan of the city, wondered how the whole would evolve over the long term: it was being promoted as being effectively static as a construct, but had elements which could or would change over time. Having seen both devices he felt that the city, once set in operation, could be described as both running like clockwork and being a kaleidoscope, and had been designed as such.
There were various reasons for this: sufficiently many people had installed themselves for their combinations as active participants to be virtually unlimited. If circumstances dictated that the kaleidoscope of participants might produce a selection that closely repeated a previous presentation there were mechanisms for variation: having a geographical distribution by surname or date of “birth”, among other possibilities. The Central Computer was capable of appreciating such patterns and their creation.
There were other agents for change which would mean that in the longer term Diaspar would be less static than initially desired by some. Even the technology that underlay the functioning of Diaspar would change over time - the programming would have to be occasionally modified to accommodate feedback loops, while changes on Earth would have to be taken into account.
The inhabitants of Diaspar were going to adapt and develop over time, whether those now choosing to go there wanted to do so or not. There was the capacity for architectural and other development and transformation so that repeated lives would find something new each time, as well as the familiar aspects. Even with the options for editing of memories people would still carry forward knowledge from previous lives, and might thus change ideas and perspectives.
There would also always be a Jester or two, artists, and various other roles, between them serving to direct the population in new directions and preventing Diaspar from becoming totally static and going into long term decline. The inhabitants would be encouraged to indulge their artistic and other interests so the city would evolve. There would still be a need for a calendar that did more than show the days of the notional year.
After some discussion amongst the city-planners and those doing the same for the land of Lys it had been agreed that the transport link between them should be maintained. It was also arranged that there should be occasional "Uniques" amongst Diaspar's population, designed to bring the two communities together, eventually, should there not have been some other cause for that to happen betweentimes. Those who had set out on the Great Journeying might return, or Vanamonde and other 'presences' wandering the universe encounter Earth - and there was always the possibility of some disaster or discovery requiring the two communities to cooperate. There would also be, at least initially, and possibly occasionally thereafter, communications between the central computers of the various communities choosing to stay behind across the many worlds.
The whole system was somewhat more complex than either the ruralists or urbanites would be presently aware of - and the details would not necessarily be revealed in the future. There were "provisions for emergencies and unexpected happenings" and the various central computers of the stay behind populations across the galaxy and beyond were in communication at least at this point of development: what they would do in future was uncertain. Eventually in the distant future stars would age and expand, and the planets, or their inhabitants would have to move: initial provision had been made and the computers were instructed to take necessary action in advance of the situation becoming critical. Given that the inhabitants of Diaspar were "within" the computers for long periods of time they could be moved to another such construct without being aware of it. The people of Lys were another matter - and would have to be considered before the situation arose. There was time enough to consider the options - and the Master's spaceship could be so used if need be - unless it was discovered beforehand and otherwise made use of.
Yarlen Zey had always had a sense of humour and a taste for puzzles. Arranging for the gaze point of his statue to indicate where the access to the rail link to Lys actually was amused him and would, hopefully, also whoever came there knowing the message.
He had considered what part he should play in the pattern through time that was Diaspar: there was only one answer. He would now be Khedron the Jester, and, whatever else he did, at least some of his appearances would overlap with the Uniques as they became old enough to start their explorings. Who better to provide them with the keys to leaving the city than the one who had designed the locks?