The third house describes your mental state, intellectual orientation, self-expression and communication, early education, mechanical dexterity and skills, immediate environment (neighborhood), and siblings. It indicates physical actions, and transportation, especially within your immediate environment. To a certain extent the third house also describes the
job or health of your mother.
Planets in the third house reflect particular facets of these matters; for example, Mercury in the third house indicates those who are natural communicators. Since communication and transportation are the areas governed by the third house, Mercury's
influence here indicates writers, teachers, publishers, salespersons, secretaries, and those involved in community projects, mail delivery, telephones, or other businesses concerned with communication, transportation and travel.