Let’s stick with the metaphor.

First, the sun is always shining, no matter how cold or dark we may be, that blazing star is fully radiant. Ananda is the same. It is the fundamental nature of the manifest.

Happiness is a conditional experience of conditioned beings and can have a manifold of relations to bliss. Happiness may cause the clouds to part, temporarily, but in my experience misery can too. Even pain, suffering, can cause bliss.

This is important: if bliss is the ground, and we are the figure, then anything that results in cracking open the figure exposes the ground.

Of course, we can’t function as broken figures, hence the universal precautions regarding spiritual practices the rupture the figure (tantra, drugs, etc) in favor of paths that slowly soften the boundaries (Govert’s “serially unfolding integral states of consciousness of the soul on her path of realization, which subtle understanding comes with esoteric philosophies like Theosophy”).

You said:

“The Cartesian error pops up in Nisargadatta, because of the construct of the ‘pure witness consciousness,’ which is posited as something radically different from one’s mind, emotions and body.”

Well, I don’t think that is correct. Nisargadatta clearly states that the whole world in part of himself. There is nothing outside. The witness, the mind, the body, the external world, are all but different aspects of himself. He explicitly said that the witness consciousness and the pure feeling “I AM” are not the ultimate all-embracing reality, but the door to realize it. Krishnamurti said the same, when stating that to “remain with what is” at any given moment is not the truth but the door to perceive the truth.

Then you add:

“While Advaita’s I AM THAT just is witnessing, even, allegedly, its own thoughts (which I think, like seeing one’s hearing, is impossible to do. You think your thoughts, you’re not witnessing them, and if you try, you will, at best, interrupt them, but not never witness them. I think).”

In my own experience it is definitely possible to witness your thoughts without being the thinker. But that development takes certain training.
When one first begins to try to witness his/her own thinking process one experiences the ceasing of the thoughts. One looks inside and there is nothing there. It is as if the attention isn’t subtle enough as to be there without affecting the thoughts, or maybe, it is because our only centre of consciousness is the thinker, and there is no center still developed behind it. At the same time, one finds difficulties in observing at once the actions the “actor” does, and the actor itself. One perceives either the action or the actor, not both.
If we keep trying, however, a kind of space between the witness and the thinker begins to be developed. Now the focus of attention comes from the witness just born as a centre of consciousness. Gradually, one becomes able to see the thoughts as a current flowing without being disturbed. That attention is gentle, non judgmental. And that attention is now embracing, including both actor and action as objects of contemplation.

I’d nuance it to “engender” as the operative term, with which I mean the actualization of possibility conditions without focusing on happiness (or enlightenment or any other higher state of consciousness) itself. Again, it’s kind of “neti, neti.” You cannot and you cannot not pursue happiness (or enlightenment etc.).

With Cartesian error I mean the subject-object split as two different realms. Happiness is not an outer state, nor an inner state, it just is. And I think it’s not entirely object-less, because it is still tied to the specific situation in which, or through which (not because of which), it arises, even to the extent that the whole of the situation—the whole of the ‘there’ of your ‘being-there’–participates. I think K gives good descriptions of this holistic nature of the bliss experience in his “Krishnamurti’s Notebook.”

The Cartesian error pops up in Nisargadatta, because of the construct of the ‘pure witness consciousness,’ which is posited as something radically different from one’s mind, emotions and body. I construe it as one step deeper into the Cartesian error, for Descartes’ Cogito is still thinking, While Advaita’s I AM THAT just is witnessing, even, allegedly, its own thoughts (which I think, like seeing one’s hearing, is impossible to do. You think your thoughts, you’re not witnessing them, and if you try, you will, at best, interrupt them, but not never witness them. I think). My working proposal/hypothesis is that both the Cogito and the I AM THAT are the intensely purified products of ego-generating reflections and subsequent ‘idealizing’ abstractions and separations. They both can be experienced as ‘really existent,’ but still are derivative ‘products.’ (I’m sure we’ll get into that in more detail later under the post “The Experiential Grounding of Theosophy.”

My perception of the exoteric nature of Nisargadatta is based on his seemingly black & white, all-or-nothing position on truth & error and enlightenment & ignorance, and thereby overlooking the careful differentiations of serially unfolding integral states of consciousness of the soul on her path of realization, which subtle understanding comes with esoteric philosophies like Theosophy. Nisargadatta is not unlike K in that respect, though with K I’m on firmer ground as far as my knowledge goes of his teachings than is the case with Nisargadatta. (This probably will have to be pursued under a different heading in connection with the nature of Krishnamurti’s teachings.)

(Sorry for dragging in so much philosophy, but it’s part of my running project, in my head that is, of updating theosophy–taken here as the synthesis of science, theology and philosophy–with post-Blavatskyan western philosophy, especially phenomenology. As it’s very experimental I invite you to join in.)

You say: “happiness seems to be the sporadic accompaniment”.
Yes, but it is sporadic because we are in a state of self-forgetfulness only for short periods. As you said, happiness is our very essence (sat-chit-ananda), but when the (lower) ego is at work as a centre of consciousness, then there is illusion, sense of separation, fear, suffering and pleasure… The very feeling “I’m limited to this personality” is the source of all that.
Because of what I said above, I don’t agree that “to frame the experience of happiness with concepts like ‘inner state’ and ‘object-less-ness’ is still within the paradigm of the Cartesian error” (neither I agree that Nisargadatta’s is a school of exoteric Advaita Vedanta, so it would be interesting to see why you make that point).
Happiness is uncaused. Happiness is the sun, our sense of ego the clouds. External means causing pleasure would be like the wind that removes the clouds, for the time being. But they are not producer of happiness. And the wind that removes the clouds will eventually bring more clouds. To be able to go beyond the clouds is to reach a real state of happiness. From that state you can see the clouds, their beauty or their ugliness, but you are not clouded anymore.
Now, there are certain (spiritual, non-ego based) activities that can lead you momentarily above the clouds, show you how it is to live in that state, and teach you how to reach that high place. That is alright. The point is to distinguish if some activity is only removing temporarily the clouds (pleasure), or is leading you beyond them (temporal happiness).

To me, happiness seems to be the sporadic accompaniment of engaging honestly and intensely in one’s ultimate concern of the moment, whatever that might be. When engaged in serving altruistically my fellow men/women there have been moments of stillness and awareness of the situation when everything seems just right and there is this sense of collective well-being that is both dependent and independent of the specific situation in which it emerged. It’s not pleasure, nor reflectively ego-centered, it just is. The most fitting oriental concept for me is Sat-chit-ananda (consciousness-being-bliss), or stated in a more phenomenologically correct way: blissfully and non-reflectively aware of the unitary and primordial state of being-embodied-among-things-with-others-in-the-world, where the mood, the situation and the pre-verbal understanding of the situation are all equi-primordial, that is, they all come intrinsically together and only through reflection and abstraction can you pry the components apart. I think, Pablo, that to frame the experience of happiness with concepts like ‘inner state’ and ‘object-less-ness’ is still within the paradigm of the Cartesian error (about which more to be said in another strand), which has also affected certain schools of exoteric Advaita Vedanta like Nisargadatta. Purposefully going after happiness will defeat its emergence, which seems quite obvious, but one can, thoughtfully and carefully, work at its possibility conditions through self-knowledge, will-to-conscience, mission-questing, skill-acquisition, intensification, and letting-go. BTW, the invoking of heaven’s intelligences through decrees and affirmations (or other rituals) as an act of service can also lead to a state of Sat-chit-ananda. It’s all in the intention and attitude. And if it will engender good health, prosperity and fun, I will not obstruct the process. Peace … and happiness. 8^)