QUOTE(Vagrant Dreamer @ Sep 20 2011, 04:34 PM)
Don't forget that the alchemists were not just readers of books and recipe followers as many 'alchemists' today are. They learned the herb lore, they were doctors and physicians of their times, and for them the correspondence was the end result of study and application, not the beginning. Alchemy is a real science, and cannot really be divorced from the work proper. The inner alchemy is carried out in the process of learning and experiencing outer alchemy. This is one expression of the, "That which is above is like that which is below..." saying.
If you want to understand the connection between the plants and the elements, planets, etc., then consider firstly what the plant is good for. How does it interact with the body? Understanding of both astrology in terms of what signs the planets are strong or weak in, and comparing this to where a particular plant has a positive or negative effect on the body, reveals the association between the plant and the planet/zodiac.
So, the moon rules the digestive system - plants which are beneficial to the digestive system might be associated with the moon; plants which put 'fire' in the digestive system might be attributed mars (inflammatory effects), etc. There is nothing more esoteric about it than knowledge of herb lore and natural medicine.
With stones it gets a little more complex because of the variations across cultures as to what stone is good for what ailment, most cultures have them though. However, planet alchemy is the beginning place for most people.
Philosophical mercury along the lines of 'salt, sulpher, mercury' and represents the physical substances on one level - the pure salts or the calcined plant matter; the essential oil; and the natural alcohol of the plant. The alcahol is universal, and is often distilled from red wine, then subsequently purified through a process of evaporation and condensation. This is the philosopher's mercury, and it's a different substance for each kingdom but it is always universal, whereas the essential salts and the essential oils are unique to each type of plant.
Fixed mercury is a different story and is a specific substance in some cases, actual mercury and molten sulfer; however it can also refer to the process of fixing the philosophical mercury as well.
Yes, I understand your opinion, about there being nothing too far esoteric about the correspondances of the Celestial bodies, but it should be understood that I understand it to play a large part in the "Mosaic Art". In which, in the skill acquired through preliminary mysticism, and after having an idea of the empty shells, their primal nature, and injecting your profound knowledge of immoveable natures therein, for example, Kether being attributed to concealed brilliance, etc. having set up this dry tree, one should study those things that are visible, the natures and effects of every part of nature, either in the immediate environment of the Magician, or on a wide scale, and injecting those shells with the other invisible natures found through the skill in Art, for the sake to awaken the power of the Imagination, so that the Knowledge of the Magician reaches far and wide, those images he produces are that much capable of joy, for he has constructed his knowledge of the invisible Conduits of God, and thus conducts his strange observations, this is when you start to see the Magician creating strange contraptions, and having them work in the most profound ways, this is an ecstasy.
And about the Mercury, for instance, I'll quote Paracelsus from his Archidoxes (an INCREDIBLE work, in my opinion, although I don't understand all of it.)
"Whoever wishes to have a tincture of the metals, must take Philosopher's Mercury, and project it to its own end; that is, from the quick mercury from whence it proceeded. Hence will ensue that the Philosopher's Mercury will be dissolved in the quick mercury, and shall receive its strength, so that the Philosophers' Mercury shall kill the quick mercury and render it fixed in the fire like itself."