Mercury, by reason of his nearness to the Sun, is seldom visible. When he does appear, he shines like a star of dusky silver color. He completes his course through the twelve signs in a little less than twelve months. Mercury cannot be strictly called either masculine or feminine, but takes on the nature of whichever planet he is joined with—masculine or feminine. By nature, he is cold and dry, and is the author of thefts, perjuries, tricks, and subtle devices.
Mercury generally signifies a person of middle height, straight and upright in body, with a long face, high forehead, and long nose. The eyes are fair, the lips thin, and the hair a sad brown or almost black—plentiful on the head but sparse on the beard. The arms, hands, and fingers are long. The complexion tends to be dark or swarthy, often of an olive or chestnut color. William Lilly observes: if Mercury is with Saturn, the native is heavy and slow; with Jupiter, temperate; with Mars, rash; with the Sun, more gentle; with Venus, more forward and showy; with the Moon, more shifting and unstable.
When Mercury is well dignified, the native is sharp and subtle in wit, with a penetrating mind and a keen imagination. He is curious in searching for hidden knowledge, an excellent logician and disputant, eloquent, apprehensive, and witty. He learns almost anything without a teacher, is naturally inclined to travel and see foreign lands, and is tireless in study and invention. Many ingenious and clever devices proceed from his mind.
But when Mercury is ill dignified, the native becomes a liar, a prattler, a boaster, and a busybody. He stirs up strife and contention, pretends to all kinds of knowledge but masters none. If he studies, his wit proves troublesome, his tongue and pen turned against everyone. He wastes time and money on vain curiosities he cannot achieve. In the end, he becomes a conceited fool, an ignoramus, or a cheat, thief, and petty pilferer.
Mercury signifies all men of letters and wit: philosophers, astrologers, mathematicians, secretaries, schoolmasters, poets, orators, advocates, merchants, diviners, sculptors, attorneys, accountants, solicitors, clerks, stationers, printers, sectaries, tailors, usurers, carriers, messengers, and footmen.
Herbs and Plants of Mercury
The herbs and plants governed by Mercury include: calamint, carrots, caraway, dill, elecampane, fennel, fern, germander, hazel, horehound, hound’s-tongue, lavender, licorice, wall-rue, maidenhair, sweet marjoram, melilot, moneywort, mulberry tree, oats, parsley, cow-parsnip, pellitory of the wall, ground pine, rest-harrow, samphire, savory (winter and summer), scabious, smallage, southernwood, meadow trefoil, valerian, and woodbine (honeysuckle).
These herbs, rightly applied, are useful to the astrological physician, who by examining the cause of disease in the nativity may find the proper remedies aligned with Mercury.
Mercury in the houses of Other Planets
In the Houses of Saturn
With Mercury in Capricorn or Aquarius, by day or by night, the native is suspicious and sharp-tongued, yet willingly keeps company with wise and religious men.
In the Houses of Jupiter
If, in a diurnal nativity, Mercury is in Sagittarius or Pisces and well fortified, the native abides with kings, manages their affairs, and is prudent in judgment. In a nocturnal nativity the same is shown, though to a lesser degree.
In the Houses of Mars
With Mercury in Aries or Scorpio, whether by day or night, the native is given to theft, falsehood, lying, and craft, encompassed with many evils, and thereby incurs much trouble and loss.
In the House of the Sun
If Mercury is in Leo, well disposed, the native wins the favor of nobles and great men, gaining friendship and gladly dwelling among them. Ill disposed, it makes one shameless, wanton, and foolish.
In the Houses of Venus
With Mercury in Taurus or Libra in any nativity, the native is cheerful and pleasant, and acquires knowledge of the arts and of all things that delight and please.
In His Own Houses
When Mercury is in Gemini or Virgo, he makes the native virtuous, well disposed, and faithful; one who attains perfection in the sciences, both practical and speculative, and is skilled in mechanical crafts.
In the House of the Moon
If Mercury is in Cancer, fortunate and well disposed, the native is bountiful and hospitable, ready to do good, not given to lewdness, but faithful, liberal, and beneficent.
From The Doctrine of Nativities, JOHN GADBURY