Alchemy

Firstly, alchemy is totally hilarious. Not just in RPGs, but in history in general. Although the thing that most springs to mind is the transmutation of lead into gold, and the pursuit of the Philosopher's Stone, there were actually a whole bunch of random other esoteric philosophical ideas and goals ranging from the creation of life in homunuli, to the distilling of the universal solvent, to the creation of a hermetic seal, to the study of the powers of planets and sacred geometry over their processes. It wasn't just turning things into other things.

Pictured: Not Alchemy

So to that end, let's look at some wacky pseudo-philosophy!


The Planets, Your Humors, and You!

All educated and intelligent people know that your health and temper are influenced by the conjunctions of the panets, and also by the balance of the four humors within your system. But what happens when the two of these coalesce and combine?

Four Humors

As everyone knows, the principle cause of all ailments is an in-balance in the humors: blood, yellow bile, black bile, and phlegm. These elements can easily be seen in a simple experiment of drawing fluid from the veins. A dark clot forms at the bottom (the black bile), above the clot is a layer of red (the blood), above this is a whitish layer (the phlegm), and the top layer is clear yellow serum (the "yellow bile"). Each of these humors has a different seat where they are created within the body, a different season of the year and of life, and a different elemental construction.

Blood/Liver/Hot/Wet/Infancy/Air/Spring
Yellow Bile/Gall Bladder/Hot/Dry/Youth/Fire/Summer
Black Bile/Spleen/Cold/Dry/Middle Age/Earth/Autumn
Phlegm/Lungs/Cold/Wet/Old Age/Water/Winter

An imbalance of these leads to differing physical and emotional signs. Sanguine folk (those with an excess of blood) are friendly, they joke and laugh around and are far from serious, they are enthusiastic, active, and social. As for their appearance they are rose tinted, slightly red, and have pretty skin. Blood was the source of energy for the body and the soul (hence vampires drinking it)  The seasonal association of blood is the spring because the natural characteristics found in individuals was associated with being hot and wet.

Yellow bile was associated with a choleric nature: bitter, short tempered, daring, ambitious, decisive, and aggressive.It was thought to be fluid found within the gallbladder, however it could also be found in excretions such as vomit or feces. The associated qualities for yellow bile are hot and dry with the natural association of summer and fire. It was believed that an excess of this humor in an individual would result in emotional irregularities such as increased anger or behaving irrationally. Physically they would appear greenish and have yellow skin. 

The melancholic are over supplied with black bile and are lazy, fearful, and sickly, also often discontented with the political system. Depression was attributed to excess or unnatural black bile secreted by the spleen. Cancer was also attributed to an excess of black bile concentrated in a specific area.The seasonal association of black bile was to autumn as the cold and dry characteristics of the season reflect the nature of man.Often they have black hair and black eyes, or maybe they just dress in black to match their mood. 

Phlegm was associated with a phlegmatic nature, thought to be associated with reserved behavior, to be low spirited, and thoughtful. Phlegm was used as a general term to describe white or colorless secretions such as pus, mucus, saliva, or sweat. Phlegm was also associated with the brain, possibly due to the color and consistency of brain tissue. The seasonal association of phlegm is winter due to the natural properties of being cold and wet. The phlegmatic were supposed to have white hair, possibly reflecting the winter of a human life. 

If all your humours are in balance, you will have a perfectly balanced personailty, and will be in peak physical health, this condition is known as being Leukine.

The humours were believed to be formed through a process of digestion, ergo your diet was intrinsically linked to your physical and emotional health. Certain foods were thought to be heating (garlic, onions, horseradish, ginger, chicken, eggs, duck, lamb, wheat, sesame seeds, walnuts, lemons, apples, and olives), and certain foods thought to be cooling (milk, fresh cheeses, mint, lettuce, cucumber, fish). Likewise certain things were held to be dry (beans, pomegranates, asparagus, dried fruits, aged cheeses) and certain foods wet (milk and dairy products, bananas, avocados, coconut, fresh cheeses, yogurt). Incidentally, this is the origin of describing certain drinks as paradoxically "dry" (a dry white wine for example).

Seven Planets

As we well know, there are seven planets, each having its own influence on Alchemy and the Humors.

Sun ☉
Metal: Gold
Organ: Heart
Humor: Hot (Blood/Yellow Bile)

Moon ☽
Metal: Silver
Organ: Brain
Humor: Cold (Black Bile, Phlegm)

Venus ♀
Metal: Copper
Organ: Kidney
Humor: Leukine

Mercury ☿
Metal: Mercury
Organ: Lung
Humor: Phlegm

Mars ♂
Metal: Iron
Organ: Gall Bladder
Humor: Yellow Bile

Jupiter ♃
Metal: Tin
Organ: Liver
Humor: Blood

Saturn ♄
Metal: Lead
Organ: Spleen
Humor: Black Bile

So what does this all mean to me?
Well, first of all I thought you might find it interesting (shows what I know, you ungrateful sods), but also there's definitely ways to make this gameable. The first and most obvious is to make for potions for various effects require the constituent alchemic elements. For example: you want a potion of resistance against fire? Well, you'll be wanting to increase your yellow bile and blood by ingesting a spicy, peppery, ginger wine infused with sesame oils and distilled to a tincture as Jupiter and Mars cross the path of the sun.

On second thoughts, you might instead need to counterbalance the heat by increasing the cold humors of phlegm and black bile? Who knows! That's what test subjects are for!

Or perhaps you need to render yourself immune to air based poisons, you will want to increase the power of your lungs by concocting a potion of mercury suspended in milk.Wait, mercury is already poisonous? Well, I don't know, you'd better combine it with a bezoar or unicorn horn or something.

Zodiac
Additionally each of the signs of the Zodiac are also associated with a certain body part, which might interact with alchemic healing or the distilling of potions. Obviously if you are concocting a potion for the clarity of thought you will want to use a cooling draught distilled when Mercury is in Aries in order to increase the phlegmatic humours in the head. However, make sure you don't mix up your constellations and planets! Otherwise you could be ushering all sorts of humours and fluids to the wrong point!

Aries Head and Face
Taurus Neck and Throat
Gemini Shoulders, Arms, and Hands
Leo Heart and Back
Cancer Breast, Stomach, and Lungs
Libra Kidneys and Loins
Virgo Guts and Belly
Scorpio Genitals and Bladder
Sagittarius Thighs
Capricorn Knees
Aquarius Legs
Pisces Feet