The resurrection of plants. Palingenesy was a concept held by some scientist-philosophers of the 18th century that offered a chemical understanding of ghosts and apparitions, an alternative to either supernatural or hallucinatory explanations. The idea of palingenesy derived from Greek philosopher Lucretius, who thought that ghosts were in fact thin filmlike products analogous to the dead skin of a snake.
The idea was revived in the 17th century among alchemists, who at a meeting of Royal Society of England burnt a plant and extracted a salt from its ashes. They then mixed the salt with an unnamed substance and subjected the mixture to heat. The particles began to move and in the midst of the powder the image (an APPARITION) of the plant emerged. When the heat was taken away the form disappeared, and when it was reapplied, it reappeared.