Mercury

Origin and etymology

The name Mercury comes from the Latin Mercurius, Roman god of commerce, travellers, messages and thieves. His Greek equivalent is Hermes, messenger of the gods, conductor of souls to the underworld (psychopomp) and a central figure of esotericism through his syncretic form Hermes Trismegistus, supposed author of the Hermetic texts in the early centuries AD.

Astronomically, Mercury is the planet closest to the Sun and the fastest: it takes only 88 days to orbit the Sun, against the 365 of Earth. Its speed projects symbolically: Mercury is the planet of the agile mind, ideas that fly, messages that arrive fast. In natal charts it always appears close to the Sun (no more than 28° angular distance).

What Mercury rules

Mercury governs the rational mind and communication: how you think, how you learn, how you speak, how you write, how you process information. It also rules short journeys (against Jupiter that rules long ones), contracts, lesser commerce, siblings and neighbours, the media. Its motto: connect the separate. Any process that involves mediation, translation or exchange is under its dominion.

Mercury enters apparent retrogradation three or four times a year, for about 3 weeks each time. In these periods, classical astrology recommends not signing important contracts, not buying new technology, not starting complicated journeys, reviewing communications carefully. It is a period of re-: review, rethink, rewrite, reorganise. More detail in the dedicated article on Mercury retrograde.

Mercury in your chart

Look at the sign of your natal Mercury: it marks your mental style. Mercury in Aries: fast, decisive, impatient thought. In Taurus: slow, deep, stable. In Gemini or Virgo (its rulership signs): agile and precise mind. In Cancer: emotional thought. In Sagittarius: expansive thought, big visions. The house where Mercury sits indicates where you concentrate your mental and communicative activity.