In keeping with the ancient Greek employment of the word, Barfield uses "metanoia" to mean the moment, personal or historical, of "repentance, or change of mind" (RCA 129).

For Barfield, the birth of Christ marks the metanoia of human history, signifying as it did the pivotal moment in the process of interiorization, the turning point of the evolution of consciousness.

See in particular "Philology and the Incarnation" (RM 228-36).