Hi Dhammasamy, I’ve edited the formatting of your post a little, I hope you don’t mind! I try to keep things neat and tidy around here.
Also, it’s helpful if, when quoting suttas, you can mention the correct SuttaCentral ID. That way your post will automatically link up with the site, and your question will appear in the sidebar for anyone who reads the sutta. Sometimes you might not know it, so that’s okay, it’s just helpful to do when you can. In this case, I think you’re quoting Ud 8.3.
Just googling that translation, it seems it is one produced by Dhammakaya. You should know that they are a criminal cult, not a genuine Buddhist group. Quoting Dhammakaya on Buddhism is like quoting Scientology on science. All of their work, as with this quote, is tainted by their lack of basic integrity and adherence to common norms of decency and truthfulness. In particular, the phrase “purest nature”, or anything vaguely like it, does not occur in the text. It is simply inserted there to provide support for their core teaching, which is that their meditation leads to the realization of the higher self, and that nibbana itself is a transcendent cosmic self. It’s rank nonsense and doesn’t deserve any serious thought.
Here is an accurate translation by Bhikkhu Anandajoti, as found on SuttaCentral.
There is, monks, an unborn, unbecome, unmade, unconditioned. If, monks there were not that unborn, unbecome, unmade, unconditioned, you could not know an escape here from the born, become, made, and conditioned. But because there is an unborn, unbecome, unmade, unconditioned, therefore you do know an escape from the born, become, made, and conditioned.
People seem to latch on to the fact that this sutta begins with an emphatic assertion. But they overlook that it is an emphatic assertion of a series of negations. It is simply confirming that there is an end of rebirth, using a slight variation of phrasing found throughout the suttas.
To understand the Sutta teachings on extinguishment—which is what the word nibbāna means—it’s useful to bear in mind two perspectives. Extinguishment is ontologically negative but psychologically positive.
That is, when discussing the existence or otherwise of the end of suffering, the Buddha consistently used negative terms, undermining the possibility of any eternalist conception of nibbana as some transcendent reality. At the same time, he painted it in glowing terms psychologically—the highest bliss, the shelter, etc.—to draw people on and overcome their fear of annihilation.