Budha

Budha, Mercury, is the fourth graha. Its presiding deity is Vishnu, its gemstone is the emerald, its element is earth, and its Vimshottari period is seventeen years. In jyotisha Budha signifies intellect, speech, reasoning, commerce, and skill with words and numbers. It is classed as a benefic, but a mutable one, its nature is said to take on the character of whatever planet it associates with, so a Budha joined to a malefic turns malefic in effect. Budha rules two signs, Mithuna (Gemini) and Kanya (Virgo), and is uniquely both ruler and exalted planet of Kanya. Because it never strays far from the Sun, it is often combust, and the tradition weighs that closeness when judging the clarity of the mind and speech. These are jyotisha's significations; the underlying body is the innermost planet.

Graha derives from the Sanskrit root grah-, to seize or grasp, so the nine grahas are seizers of a nativity rather than planets in the strict astronomical sense, a definition broad enough to include Rahu and Ketu, calculated points with no physical body, alongside Budha, which plainly is one. Budha's inclusion in the sevenfold, and later ninefold, scheme reached Sanskrit astrology from Greek horoscopy through the Yavanajataka, a Sanskrit versification of a Greek astrological text from roughly the second to fourth centuries CE, which carried with it the dignities, exaltations and planetary week built up around bodies India had tracked for far longer on its own terms. The particular significations, gemstone and dasha length jyotisha now assigns Budha belong to a later classical layer of the tradition, standardly attributed to compilations such as the Brihat Parashara Hora Shastra, dated to roughly the seventh or eighth century CE.

Sources Brihat Parashara Hora ShastraSage Parashara (attributed) with Jyotihsastra: Astral and Mathematical LiteratureDavid Pingree, The Yavanajataka of SphujidhvajaDavid Pingree

A graha is not read in isolation but through the several tables that make up a Panchanga and a chart. It rules Wednesday in the seven-day week, which in the Indian tradition as in the European one is named for the seven visible grahas in the order of the planetary hours. It holds 17 years of the Vimshottari dasha cycle, and it is lord of three of the twenty-seven nakshatras, Ashlesha, Jyeshtha and Revati, spaced nine apart so that the nine grahas cover the twenty-seven exactly three times over.

The Vimshottari dasha system divides a notional lifetime of 120 years among the nine grahas in a fixed order, Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn and Mercury, with fixed lengths that sum to exactly 120. Which period a person begins life in is determined by the nakshatra the Moon occupied at birth, and how far through that period, by how far through the nakshatra the Moon had travelled.

In the scheme of dignities it is exalted in Virgo, which is also one of its own signs, and in its fall in Pisces, and dignity is what the classical rules for strength are built on, since a graha in its own sign or its exaltation is read as able to act and one in its fall as constrained.

Mercury is the only graha whose sign of exaltation is also one of its own signs, which collapses two of the usual dignities into one and makes its treatment slightly irregular throughout the corpus. It is also never far from the Sun in longitude and is therefore frequently combust, a condition the tradition reads as weakening, so a rule requiring a strong Mercury is a rule that will often be qualified.