Alchemy worked as a disguise because it was a good one. A text about roasting lead, dissolving sulphur, and joining mercury and salt, who would burn that? The Inquisitors of the 13th and 14th centuries knew little about chemistry and cared even less. So alchemical texts passed freely through channels that would have been deadly if people had understood what they really carried: a step-by-step method for taking apart the conditioned self and building a free one. The best alchemists said this openly, but only to those who could read the code. Paracelsus put it this way: 'The art of alchemy is not the art of gold-making. It is the art of making gold.' In context the difference is everything. Physical gold is not the point. The gold of the self, what every tradition names differently while pointing at the same thing, is the whole art.
The proof that alchemy was never really about physical gold is simple. If even one of the hundreds of serious alchemists over twelve centuries had actually turned lead into gold, the effect on the economy would have been obvious and recorded. None was. What did get recorded, in their diaries and notebooks and coded treatises, were dramatic inner changes: states of deep insight, experiences of union, the falling away of fear, new strengths that had not been there before. Those are not side effects of chemistry. They are the main results of a careful inner practice that used chemical language as its cover.
Manly P. Hall described three levels of alchemy that a serious practitioner worked at once. Physical alchemy was real lab work with real materials, and it produced real discoveries, aqua regia, distillation methods, the mineral acids, that became the foundation of modern chemistry. The lab work was not fake. But it was also a mirror. Psychological alchemy was the inner work of turning the raw material of the unconscious personality into the gold of an integrated mind. This is the main level, the real Great Work, and every chemical step has an exact psychological match. Spiritual alchemy was the work of lining up the individual soul with its divine source, what the Hermeticists called the return of the Nous to the One. These three were practiced together. The lab work fed the inner work, which fed the spiritual work. They were not separate activities. They were one activity at three scales of reality.