When Mercury is in Sagittarius, our thinking shifts from a need to plumb the depths of any given situation (Scorpio) to the desire to learn about a wide range of topics. Mercury in Sagittarius gives a just, honest, generous and sincere mind, suitable for expansion through higher education. Ideals are sought, our thinking is more optimistic, and our faith increases. 

You are very active mentally, but somewhat changeable - studying more than one subject at a time and quickly passing from subject to subject. You are direct in speech and say exactly what you think. We are more equipped to believe and to persuade. What is fair and unfair concerns us most now. However, we are not always very precise under this influence.