Mercury in the 9th house is a very fortunate position, as both the significations of Mercury and the 9th house flourish. The person will be religious or spiritual in a very intelligent way He may be given to studying scriptural knowledge and will understand such matters in great depth. He will be very interested in understanding many different philosophical viewpoints and metaphysical subjects. He will also be interested in meditation or chanting, and may worship the God Vishnu. He will benefit from his father, who may be refined, intelligent, and long-lived. The person will enjoy long-distance travel and may visit foreign countries several times in his life. He will be learned, scholarly, and well educated. He will be a good speaker. He will be cultured, refined, and well mannered. There may be talent in math, science, or astrology. The person gets along well with his guru or spiritual teachers, and is always lucky in obtaining knowledge. He has good luck and will find solutions to problems that arise in life. There is a good deal of wisdom, and the person performs good deeds. If Mercury is conjunct with or aspected by a malefic planet, it loses its benefic status and the results are reversed.

UCHCHA and SWAKSHETRA (exalted and own house). If Mercury is in Virgo or Gemini in the 9th house, the benefits described above are magnified. The person is extraordinarily intelligent and wise. He is highly fortunate in gaining all kinds of higher knowledge. He is extremely lucky and will always find solutions to his problems. He will travel to many foreign countries in his life. His father will be prosperous, long-lived, and intelligent. The person may be a philosopher or spiritual teacher. He is cultured and refined, and constantly performs good deeds.

NEECHA (fallen). If Mercury is in Pisces in the 9th house, the person may be lacking in discriminative ability in regards to religious or spiritual matters. He may get a fraudulent guru or receive false knowledge. He will have troubles in gaining higher knowledge. His luck is spoiled. He will have disturbances in his relationship with his father, who may be weak, sick, or mentally unsteady. The person is lacking in wisdom. He will travel rarely or experience difficulties when he does. He may have no interest in performing good deeds or in practicing religious rites and rituals.

Source: «Ancient Hindu Astrology for the Modern Western Astrologer» by James Braha