When I did a Dewey Decimal analysis of my writing using that AI at http://act-dl.base-search.net/textclassifier – then weighed for frequency and its own confidence level, 115 TIME was my first and 120 Epistemology, causation and humankind was my second, with 122 Causation as my third.
I suspect we’re all speaking in the same field. Alas, there are not too many books specifically any of those subjects.