Alchemy in Ibn Khaldun's Muqaddimah

Alchemy in Ibn Khaldun's Muqaddimah: "Ibn Khaldun continues........

Here ends the discussion
by Ibn Bishrun, one of the great pupils of Maslamah al-Maj'riti, the Spanish
authority on alchemy, letter magic, and sorcery, for the third [ninth]
century and later (times). One can see how all the expressions used by
(alchemists) tend to be secret hints and puzzles,difficult to explained
or understood. This is a proof of the fact that alchemy is
not a natural craft."