Alchemical symbols were devised ways to represent elements, compounds and other things related to alchemy. Alchemy was a kind of chemistry and speculative philosophy that aimed to turn ordinary metals into gold, discovery a cure for all diseases, and find the secrets of eternal life [source].
These symbols were used until the 18th century, and became more or less standardized over time. However, there was some variation in the appearance and use of the symbols between different alchemists.
As well as being associated with elements and compounds, the symbols also have other meanings and associations. For example, the fire symbol is associated with warmth, heat, dryness, the colours red and orange, with love, passion, compassion, hate, anger and other 'fiery' emotions, and is considered masculine/male.
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