What Is the Doctrine of Signatures?
Agrippa writes:
“The properties of things are known by their forms, figures, colors, smells, tastes, and other accidents. These are the signs, or signatures, by which the occult virtues are revealed.”
In other words, every natural thing bears a mark—a visual or sensory clue to its hidden spiritual power. This “signature” is placed there by the stars, angels, or God. The trained magus reads these clues to unlock nature’s secrets.
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Examples of Signatures
• Walnut: Looks like a human brain. Its inner shell resembles the corpus callosum. Therefore, it strengthens the mind.
• Liverwort: Its leaf resembles a human liver → used to heal liver ailments.
• Sunflower: Follows the Sun’s path. Ruled by the Sun → used for vitality, glory, success.
• Poppy: Its milky sap induces sleep → ruled by the Moon and associated with dreams.
This concept goes beyond herbal medicine—Agrippa says the appearance, taste, scent, and even movement of a plant reflects its occult virtue.
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Agrippa’s Method for Determining Plant Virtues
To Agrippa, every plant has:
An elemental alignment (Earth, Air, Fire, or Water)
A planetary ruler (Sun, Moon, Mars, Venus, Mercury, Jupiter, or Saturn)
Zodiacal influences
An associated angel or spirit
Magical virtues and uses
Agrippa gives us tables of correspondences matching herbs to stars, signs, and spiritual forces. Here are a few examples from Book I and Book II: