Four element theory is on approximately the same epistemological plane as modern personality psychology. In some ways it's more useful than psychology, because

Four element theory is on approximately the same epistemological plane as modern personality psychology. In some ways it's more useful than psychology, because it has a straightforward logic in terms of metaphor and relationships between parts, whereas psychology is a mess. Of course, it has very little to do with how the brain works, but psychology also has very little to do with how the brain works (it's more about the use of language to describe and regulate behavior), so it's not a big deal.