How does the nondual teaching answer the question of “the one and the many” as well as that of “why there is something rather than nothing?”

So far as I have seen, it tends to offer two explanations: ontological and epistemology. I’m more familiar with the latter, and I find it more compelling.

I. Ontological Explanation

Here’s Bernard Kastrup from his excellent paper “The Universe in Consciousness” (PDF):

I submit that (a) experiences are patterns of self-excitation of cosmic consciousness and that (b) cosmic consciousness has the inherent disposition to self-excitation. [my italics]

The ontological explanation states that all that exists is universal consciousness. So far, so good. And yet, it’s obvious that there are experiences: intermittent appearances.

(a) It has to account for the appearance of experience in terms of its unity and thus it states that experiences are nothing but “patterns of self-excitation of cosmic [or universal] consciousness.” Analogy: Just as a whirlpool is just a pattern of self-excitation of water, so experiences are nothing but patterns of vibrations of universal consciousness.

(b) The bigger fish to fry has to do with why there’s any “thing” in the first place. And the best this ontological account can do is to simply say that universal consciousness has “the inherent disposition to self-excitation.” That’s a posit, of course, not an argument, but as Vivekananda points out, you can’t explain the whole in terms of its parts. If you ask, “Why is there manifestation?,” you’re making a category mistake: you’re trying to explain the spaceless and timeless (undifferentiated universal consciousness) in terms of spatial and temporal concepts. It’s not possible.

II. The Epistemological Explanation

There’s only universal consciousness. There’s only the appearance of multiplicity and diversity.

That appearance of multiplicity and diversity is owing to the nature of the finite mind: the finite mind is to be understood in terms of namarupa (“name and form”). An analogy: If one looks through red glasses, one sees red color. If one “looks through” the finite mind, then one sees an apparent multiplicity and diversity of thoughts, feelings, sensations, and perceptions.

When “this piece of technology” known as the finite mind is “taken off,” then what’s left is unitary, undifferentiated universal consciousness: the white light of eternity, as it were. This could be called nirvikalpa samadhi, which, like “sudden awakening” in Zen, is not the same thing as being ultimately established in and as consciousness.

I speak more about this issue during the last couple of minutes of this video essay. Go to the sensory deprivation thought experiment: