The 3rd house is the house of the immediate environment, contacts, the house of specific thinking, primary and secondary education, and short-distance travels. Mercury is the symbolic ruler of the 3rd house, so this is its house, it manifests itself naturally here. Mercury in the 3rd house will show us a person of specific mind.
Such a person sees the nearby space well, is excellent in it, pays attention to details. And in the issue, subject that interests him, he possesses detailed knowledge about it. Remembers all the facts, checks everything in practice.
Clearly and clearly expresses his thoughts, both orally and on paper. Excellent orientation in the current situation.
The person with Mercury in the 3rd house usually has many connections and various contacts. But they are all essentially necessary for him for business. Of course, we pay attention to the sign in which Mercury is located. In the earth sign, these are more often business contacts necessary for work; in the water sign, more emotional connection in the immediate environment of relatives, friends, neighbors (our closest environment, everyday communication). In an air sign, these are usually friends with common interests, with whom there is an exchange of information, and in a fire sign, these are friends who are ready to listen to the person's ideas and knowledge.
Owners of Mercury in the 3rd house often choose a profession in the Mercurian sphere - these are journalists, communicators, managers, consultants, sellers, drivers, taxi drivers, carriers and everything related to training, teachers, educators.