(to watch video just click the title)
There are two ways you can look at Alchemy, one is they didn't understand what they were doing.
Or, two, they díd understand what they were doing.
M. M. Pattison Muir; The Story of Alchemy and the Beginnings of Chemistry.
You can find the Internet Archive page HERE, and listen to somebody who doesn't understand symbolism.
Alchemy, Sacred Secrets Revealed 2008 is a documentary by scientists who took the time and trouble to understand what this was all about.
It is about science, and science had to be hidden from the bloodthirsty church and their inquisition.
If you was not carefull you could end up at the stake, or worse !!!
The dark ages are called so for a reason, knowledge and litteracy were kept from the people by the church.
Never forget, knowledge is the death stroke for religion: it proves they are lying!