What proof is there that a stone actually exists that can give enlightenment and allow you to fly through space?
I don't know what proof exists, if there is any it is likely kept secret.
What we do know is that if you follow the multitude of alchemical texts, documents and treatises then you DO see the things they say will be seen. You see the colour changes predicted, you smell the odours predicted and so on. This surely lends a level of credibility to the works but yes, doesn't reprsent proof of the claimed miracle effects of the Stone.
However I figure this way
The Stone, it's claimed benefits and the processes for making it are recorded in literally 100s if not 1000s of works spanning centuries.
Why would all those people go to so much trouble to perpetuate a total hoax and do so in such a cryptic way that 99% of the human race will either never read their works or if they did would not understand them? Just doesn't make sense for it all to be a hoax.
Then add to this the fact that the Stone, its processes and colour changes and benefits are recounted in just about every religious tome across the world. The same secret, which is recorded allegorically and cryptically using the same allegorical terminology in all these works, the Bible, the Quran, the Bhagavad Gita, in Taoism, Rosicrucianism and so on. It's clear to me that this secret spread out of one place and went out to all the world and was translated into all the different languages and religions and cultures.
All in all if the Stone were a hoax then it is the hoax of all time, of all humanity spanning 1000s of years and 1000s of documents and 1000s of key people. That's just too out there to be true imo.
The Stone is a real concept. It can be achieved. But it is god like power and thus hugely dangerous. We don't teach the public how to create a nuclear bomb. We do teach people science. They might ultimately come to know how to make a nuclear bomb, but by then they would be an enlightened scientist.
I suspect that Ariadne's Thread is a test of some sort. An educational labyrinth bestowing groundwork knowledge to the alchemist, bringing a form of enlightenment and understanding. I suspect that once one reaches a certain point of understanding and proficiency one would get a visitation from those totally enlightened and perhaps an invitation to move from their current life to go live among the enlightened and learn more and more in a safe and controlled environment. Thus the concept of "Bensalem" in The New Atlantis by Sir Francis Bacon.