In popular cultures, alchemists have been portrayed to turn one element into another, a process which can be called "alchemical transmutation". However, serious students of occultism have well known that turning a crude element, such as lead, into a finer element, such as gold, is symbolic, for the true purpose of alchemy is not for transmuting the body, but the mind.
In Hermetic Alchemy, the transmutation rituals are performed as a smaller part of the bigger work — to transmute the mind. The lead is a physical substance, which represents an impure mind, while the gold is a physical substance, which represents a purer mind. Therefore, the rituals are performed in the physical plane for the purpose of refining the mind of the alchemists in the astral plane.
An alchemist, as well as a layman, who only focuses on the physical outcome of successfully turning lead into gold, sets his or her goal wrong. The true meaning of the alchemical transmutation has never been to earn the more precious metal, but to attain the purer mind. Even though it is not a main goal, obtaining of the gold, if actually having been successful, is quite an essential sign, showing that the mind of the alchemist has become purer than ever, because what happens in the physical plane is a lower manifestation of that in the astral plane, according to a proverb of Hermetic Alchemy: "as above so below."
A miracle like turning a crude metal into a precious one may sound appealing, but it also serves other purposes. In the middle ages, and perhaps earlier, It was a way for an alchemist to rally support from princes, who were interested in enriching their coffers. More interestingly, it also serves a test of greed against self-sufficiency — the more greedy the alchemy is, the less likely that she or he will achieve the true goal of the Hermetic Alchemical Transmutation. It is not that the alchemist will not be able to turn a crude metal into a precious one, provided that is is actually possible. Still, the lust for wealth in the alchemist's mind is the fact that the alchemist has not achieved the goal of the Hermetic Alchemy, as it truly is to transmute the mind, not the body.
A more advanced alchemist can perform the transmutation ritual without resorting to any metal or even any physical substance, but his or her own body and, more importantly, his or her own mind. Alchemy is a practice of the mind, in order to attain self-realization and self-reliance. No matter how matters in the physical plane are crude, the alchemists' mind in the astral plane must be seeking purity. And if possible, after the purity of mind is obtained in the higher plane, the mind will lead to purer physical manifestations in the lower plane. That is the true goal of the Hermetic Alchemical Transmutation.