The philospoher’s stone is both liquid and stone. “One and the same thing. That refers to those two aspects of the realization of the Self: something firm is born [physical self and conscious]… and at the same time is born something very living part in the flow of life, without the inhibitions or restrictions of consciousness [the higher self]”
“With the help of the instinct of truth, “Instinctive truth is a manifestation of the [Higher] Self..,It is something which operates in every human being, a discreetly quick word which the [Higher] Self whispers in your ear …”, life goes on as a meaningful flow, as a manifestation of the [Higher] Self. That is the result of the coniunctio. In many other cases it is described as the philosopher’s stone.”
So once you are connected to your Higher Self, Higher Self can manifest in your physical daily life through instinctive truth. So Higher Self and Consciousness are harmonized on the physical plane.
In alchemical language the philosopher’s stone represents the truth without reflection, instinctive truth, which is the connection with Higher Self.
Thus it is believed that once you have the philosopher’s stone, you will have eternal life.
Information gathered from Alchemy by Marie-Louise Von Franz