"To turn Lead into Gold" is a metaphor.

To elevate the thoughts of the mind, from base thoughts (Lead)
to ideas the exist in and of itself, which is "THOUGHT" itself (Gold) .

Schrodinger and Heisenberg were one of the first to make a bold step
in this direction of thought, which gave Theoretical Physicists:

"Schrodinger’s Cats Paradox" and "Heisenberg’s Uncertainty Principle".

When Theoretical Physicists start to contemplate the immeasurable
thought-form known as Time, they will understand they are pondering
an idea that is Life itself, which exists beyond Light and
IS ENERGY.

Therefore:

TIME = The Philosopher's Stone

When a mind ponders "Time" (The Philosopher’s Stone),
The Stone's Energy, gives that mind "Life."

The physical representation of "Time,"
that is, The Philosopher’s Stone is:

Common Table Salt.