Zettelkasten == System 1.5 ?
Fleetingzettelkasten == system 1.5 ?
The system 1 gives automatic information that you did not think about, by association.
The system 2 is a controlled, conscious construction of information
The zettelkasten is a conversation partner that provides old ideas by association, but is still controlled consciously. It lies at the frontier between the 2 systems.