Humans have always sought to externalise themselves: their work force entrusted to animals and then to machinery, their memory entrusted to writing, their computing capacity entrusted to computers, their trust materialised in money, their digestion partly entrusted to cooking, their decision-making power entrusted to rulers, their discernment capacity entrusted to the media, their autonomy entrusted to society.
The primary (agriculture), secondary (industry) and then tertiary (services) sectors saw the population shift from one to the other in this order. What is the quaternary sector that will receive most of the population when the tertiary sector, like its predecessors, no longer needs all the people it now employs?