The above only-two-things thing is the nondual insight reduced to twenty-one words. The next step down is two words — not-two — and the next step after that is a single symbol:
The term and the symbol only represent nonduality, whereas the twenty-one words tell the whole story. There’s really nothing else to know about nonduality, nothing else to say; the rest is just a matter of extrapolation and results processing. I, who’ve probably written more on the subject than anyone, can’t think of much else to say about nonduality itself. There’s plenty to say about the peripheral issues involved in achieving nondual realization, but about nonduality itself, not much and nothing new.
Unlike any belief-based system, if we were stranded on a desert island with no books or resources and just our own faculties for company, we could build a true and complete cosmology/worldview/religion from just these twenty-one words, in fact, a deserted desert island might be the ideal environment for that work. Given time, a brief description of Last Thursdayism might also do the trick, and as an absolute last resort, thinking would also work, but the twenty-one words are the shortest distance between not-two points.