The philosophers stone was apparently never discovered as an external, material phenomenon. And so if it exists at all, perhaps rather than it having an external reality, it may actually be an internal, human one. Perhaps the stone is a seat, where the observing consciousness of our loving wisdom, or true nature dwells. With this understanding, it could also be considered to be the cornerstone, or foundation of our existence, from where no stone or word is left unturned. (Please see contemplations on Self and True Nature).