Mercury placed in first house of horoscope is beneficial only in case if sitting alone. If it is sitting with any sinful planet like Sun, becomes malefic. Having mercury in first house of horoscope the native is intelligent, he can be married at young age, he will be long lived, belief in God, will be comic flair.Mercury in first house gives earnings through writings and the person is thrifty and dear of bride class. If mercury placed in Gemini, Libra or Aquarius the native can be an artist and becomes a great speaker of assembly. If mercury placed in Sagittarius the person is fearless and fair. When mercury placed in Scorpio, the native is a harsh speaker and in in Virgo, Capricorn, the person can become a successful business person or high official in a company. But according to the nature he is not successful in society, as he speaks less, do not meet people without any reason and do not make many friends. He is always interested to make relations with others wife. Native may be less educated due to interruptions in study but still he is very intelligent. according to my experience mercury in first house of horoscope make the native practical about the dissension of his life, he or she never compromise with their comforts due to emotional things. but due to other planets conjunctions with mercury or aspects on mercury can change the results accordingly.
Astrologer Sunil Kumar