Correspondence tables present us with a classification model based on magical energy allowing us to see energetic relationships between things. They are generally charts that show the relationships between different things that have similar character energetically. At their most basic level, these correspondence tables allow magic users to make quick decisions about spell ingredients, timing and by grouping different items together symbolically according to their Intent, or, more typically, the planetary or elemental energies most closely aligned with their intent.
In the Western correspondence system, each planet or element symbolizes a collection of characteristics. Plants and crystals are then simply organized under the headings of those planets and elements that best matches its natural characteristics. It’s not so different from the modern Linnaean taxonomy except that the Linnaean taxonomy focuses specifically on how the plant reproduces and so combines plants into categories based on evolutionary relationships, which the Western correspondence system combines them into categories based on perceived energetic similarities. Gemini, is ruled by air (and Mercury) because it is associated with air (and Mercury) things, like communication, seeking knowledge and travel and Taurus is ruled by Earth (and Venus) because it is associated with Earth (and Venus) things, like the fertility and growing things.
Where Correspondence Tables Come From
Throughout history, scholars have sought to understand the world through categorization. The earliest scholars of the natural world were magicians, priests, shamans, astrologers and philosophers. They categorized things in ways that are meaningful to them; by comparing them to other things in the natural world, and according to their magical and medicinal uses. These are the basis for modern tables of correspondences.
The astrological correspondences are classification systems derived from ancient alchemical and healing traditions. The Western elemental correspondence system derived as a theoretical construct in ancient Greece. The the planetary system probably originally developed independently and then the two systems combined. The planets represented by Gods who epitomized the specific characteristics of each category. These systems were mostly used by physicians. Basically, each element or planet corresponded originally to a body system and the plants that were used to treat that system were assigned those correspondences.
Different criteria were used to determine the correspondences of plants but many correspondences came from the doctrine of signatures, even before it was idea was codified. This assigned meaning to the physical appearance of an herb or its growth habit. Walnut looks like a brain, so it must be good for the brain, for example. Others categorized things according to their properties and aligned them to the properties of the planets, unpleasantly hot or caustic things must align with Mars. Later, elemental correspondences inherited properties of the planets with which they were associated and as new items were discovered and added to the magical formulary, they were assigned correspondences accordingly. Because these were European-based practices, some New World plants have only recently been categorized under this system as they would never have been seen by ancient physicians. Different practitioners suggested different correspondences then as they do now. Some systems were limited to herbs, others to minerals, and these were combined. Later, other objects and symbols, even ideas were added and the system continues to grow.
There was once not so much as a fine line between medicine and magick, but a split occurred and it seems magick-users took the system with them and broadened it and adapted it away from its original specific use. While physicians have no interest in Tables of Correspondence, they remain relevant to the magic user. They allow us to quickly look up what items contain energy that corresponds to the intent of our spell working. For example, we know want to do a spell to encourage open dialog, we might choose a collection of herbs, crystals and other objects that are associated with the element of Air which relates to communication, and/or Mercury because this also relates to communication and perhaps perform it in the sign of Gemini (more communication) or Libra which relates to fair and equitable exchanges. Timing and materials sorted, we can now focus the particulars of a spell.
Because there are many different traditions and many different ways of looking at magical energy, you may find that correspondence tables vary. You may find that you look at the ascribed correspondence to an item according to one source and find that it doesn’t ring true to you. In truth, each of us has our own unique experience and that which is symbolic to one person might not be to another. If you disagree with a stated correspondence, try to determine what prompted it. If you simply cannot come to agreement with your source, go with your gut.
Linneaus categorized plants and animals according to their reproductive traits in the 1700s and brought about our modern methods, which are also useful to know, especially for wildcrafting and plant identification. You can find herbs listed according to the Linnaean classification system at Herbs Listed by Botanical Family.
More Information Online
The School of Evolutionary Herbalism has videos based on alchemical principles and explains planetary correspondences of herbs quite well in this video https://youtu.be/BRAMnjxeIXA