So, lets see what Mercury can do in 1st house without any conjunction or aspect from any other planet. 1st lets see what these 2 things represent --
Mercury represents communication skills, marketing, calculative ability, younger siblings, hobbies, skills with hands, intelligence, quick decision making, logical thinking, youthfulness etc.
1st house/Ascendant is your self, personality, overall health, life path and head in human body etc.
So, when Mercury comes into 1st house, first of all this person is really communicative. Communicative by any means, written or oral. So, are there only these 2 ways to communicate? Not really. Sign Language, communication through media, movies, by performing your art and talent on stage. These are all ways to communicate with other people and when Mercury is in 1st house, these people want to communicate through any or all means of communication. They just want to communicate to all people around them. Communication becomes their life path. :P .
Mercury is basically the Prince, Son of King, whom King used as a messenger to go at different places to communicate the King's message. So, Mercury is forever moving. It doesn't want to stay at one place. So, if you think we are meant to do one job at a time only, then these people with Mercury in 1st house are exceptions. They can be at many different works at same time and can easily handle them. As Mercury is businessman and it is in 1st house of life path, most probably these guys become businessman in life. Mercury is also intelligence and 1st house represents head/brain in human body, so these people are highly intelligent. As Mercury also represents young age, these people are forever youthful and charming. They are actually the people who can say that "Age is just numbers".
Actually, the easiest way to find if Mercury is working fine in your life or not, is to ask yourself that how good you are in calculations without any technical help? If you can calculate fast without use of any instrument, your Mercury is working fine.
From 1st house, Mercury aspects the 7th house of spouse and business. Hence, it is very necessary for these people to have a spouse who is communicative like them. They always want to communicate with their better half. For business also, they look for business which is communication oriented. Call Centre is just one example.
Hope this helps.
Tomorrow - Mercury in 2nd house.
Vishal S Saxena - Astrologer