3rd House
The third house is the house of your immediate circle and exchange: siblings, neighbors, short trips, everyday communication, and learning.
What the House Rules
The third house rules how a person communicates day to day: messages, conversations, paperwork, the commute, early education.
Classical astrology also assigns siblings to this house, and horizontal family ties in general.
Planets in the House
Mercury in the third house amplifies everything Mercurial: many contacts, lots of information, ease of speech.
Mars here brings sharpness in conversation and arguments with relatives, Saturn reticence and difficulties in early schooling, the Moon emotional involvement in communication.
Sign on the Cusp and an Empty House
The sign on the cusp describes the manner of speaking: Virgo precise, Leo vivid, Scorpio evasive and probing.
An empty third house is read through its ruler. It is often empty, and that doesn't mean the person is quiet.