Throughout time, there have been many languages created that have given meaning and purpose to civilization, but have also aided and abetted to hide certain secrets. Secrets that throughout the ages have helped those who know how to translate it and utterly confuse others who have not sought "the lost knowledge". Take a look at an old alchemist's notebook, and all that one sees is scrawling of some near unintelligible pictographs... unless one knows how to read it.
Alchemy has long been held as a pseudoscience and the predecessor of modern science as it is known today. It conceives in the imagination almost like a dream, placing an old man bent over from the weight of his studies shrouded in candlelight and dancing off beakers full of dark and mysterious material. His eyes are half-closed as he relentlessly continues through the night in search of what was known as the "Elixir of Life", guaranteed to give the pursuer immortality. In other tales, this old man would be trying to change the heavy weight of lead into a weight of gold.
However, what is usually not known about alchemy was what it meant to several other budding scientists at the time in search of something deeper, something more. These scientists and philosophers created different camps between the physical alchemists and the spiritual alchemists that would inspire a schism between the seekers of truth via the pursuit of knowledge. The physical alchemists were part of the contributions to modern science while chasing a pipe dream of endless wealth or endless life. The spiritual alchemists looked deeper into what this science from the Middle East was telling them. They suggested that this "science" was more of a philosophy to become a more self-aware person, capable of a different type of wealth or life than how humans define the two terms.
Google "alchemy symbols" and one will receive a plethora of charts dictating certain symbols and their corresponding materials and processes. The most common alchemy symbols that will first be encountered are the materials often used. For the physical alchemists, this was almost always signified with lead, heavy and basic. While the spiritual alchemists agreed on the symbolism therein to a point, they interpreted this as a sign of the raw, wild, and unfettered self that was yet to be tamed by the person's own being. It was the starting place for all those who were yet to be "enlightened" or "awakened" as many people nowadays say. People in this state remained unaware of their flaws, the effects of their actions, or even their own place in the world as they continued consumed by their own thoughts without much consideration for their thoughts. Their minds, bodies, and spirits were not united as one coherent person in harmony, but rather existing with their fears, limits, and inner darkness. This is due to no one's fault, they hypothesized. In fact, everyone starts out here, but it is completely up to the person to take charge of his inner universe and seek the truth within, whatever that may be.
Another one of the common alchemy symbols often used is gold. Once again, each scientist/philosopher had a different stance on the issue itself. Gold or the Elixir of Life (or even the Philosopher's Stone to some accounts), to the physical alchemists, symbolized their final ending point, their completion of their work. They had attained the limitless wealth or immortality they had sought. Once again, the spiritual alchemists agreed to a point. Yes, it did mean the completion of the work they did. It did mean the final point and attainment of immortality, but in a different light. This was and still is complicated to imagine, but however when one seeks out the words of Buddha, Jesus, Mohammed, and many other such religious figures and their own everlasting immortality in our minds, perhaps it is not so far-fetched to imagine.
All in all, whether it is for spiritual pursuits or science, the real secrets of alchemy lie with the alchemists who originally scrawled those notes in those ancient parchment papers. Their own words can only be interpreted and imagined. That would require a contact with those of everlasting life to understand what exactly is being said.