The boundary separating system and environment is not like a physical, spatial boundary that can looked across or traveled across. It is more accurately described as a horizon, and horizons are ever-receding. The system can assume that something exists or awaits beyond the horizon, but whatever it is can never be reached. Indeed, every system operates on the assumption that something else is out there–something other than itself or something other than now. A social system, as communication, expects continuity. It makes no sense to make an offer of communication when no response is expected. If I offer someone money, for example, I expect them to accept or decline the offer. No response at all it inconceivable because for the other person t stand there and do nothing would be interpreted as declining the offer.
Inevitably, we are confronted with a paradox in the search for unity, that is, with the demand to continue. For observers are autopoietic systems that can only produce their operations on the assumption that other operations will follow. The world is therefore an endless world, a “horizon” always holding out the prospect of other possibilities.
(A Systems Theory of Religion, 50)
This is also why consciousness cannot conceive of its own death or ending. It cannot operate without the assumption that something else is always coming.