For Thomas, the advantage of explicating the Trinity by reference to knowing and willing was that these are two human processes that remain within the soul.  They remain within the realm of praxis.

Jenson notes that the great achievement of Barth’s Trinitarian theology is to start elsewhere, not with “self-contained” knowing and willing but with the “self-revealing” God.  Barth moved Trinitarian theology where it belonged, into the realm of poiesis.