The conceptual foundation of is to be found in the "enlightened rule" of monarchs practised in 18th-century Prussia and other German states. These states did not accept "radical" concepts such as democracy or popular sovereignty, but they did struggle to professionalise their public services and to reduce corruption and favouritism. The idea was that whoever represents the state by undertaking official duties which only the state may legally provide ('), such as issuing official documents, teaching state-approved curricula to students, preaching in state-approved churches, or making any other kind of official decisions, should have a special legal status and relationship with the state characterised by a higher-than-normal degree of loyalty. At its core, that loyalty is regarded as mutual, with having a special duty of service (') going beyond the duties of salaried workers, with the state having a special duty of seeing to their welfare ("") that likewise goes beyond what would be expected of a commercial employer.