This I did as a thing to CG Boost challenge theme "Alchemy".
My taking is that most recipes alchemists did to create the stone of eternal life or "Philosopher's stone" was instantly lethal. Using things like Quicksilver, sulfur, lead and so on made it rather much like poison a body.
So, I was thinking that they that succeeded saved their soul and mind in this world for eternity... and are now among us as old ghosts :).
All is in Blender and almost everything when it comes to material is done procedural inside Blender.