Owen Barfield regarded himself as doing a mixture of 'scientific/ empirical' and epistemological research - but to understand him I believe we need also to know (or infer) the fundamental, metaphysical assumptions which underpin and make sense of the rest.
By scientific/ empirical I mean especially Barfield's work on 'philology - the history of word meanings and their transformations; and what that history implies about the societies using the languages. And by epistemological I mean the philosophy of how we know, the basis or justification for understanding.
But underneath both of these are the metaphysical assumptions about the way that reality is 'set-up' - its structure, meaning, purpose etc; including what is our own personal stake in reality: e.g. Why we should care about this stuff! Why it is important to us individually and in what way?