Mark Phillips' Pages: Workbook: 10/14/21: I suspect (but don't claim to know for certain) a main source for what later became Phenomenology in the broad sense:

Mark Phillips, "Plotinus" (2023) — Mark Phillips, *Plotinus* (2023)

October 14, 2021:

I suspect (but don't claim to know for certain) a main source for what later became Phenomenology in the broad sense: consciousness or subjectivity undergoing a process of graduated evolution.