WHY do we say "Good morning"?

United States
@bunnybon7 (20159)
August 22, 2010 1:09pm CST
I used to be so happy in the mornings before my disability. Lots of people would just hate me and say shut up already. Then, i got sick 6yrs ago and never feel good. especially in the morning. now im the one that could strangle someone when they say Good morning. sons gf's,every time he gets one, knows im not a morning person. and yet, they always say good morning... i know its just cranky old me so i say it back, minus the good...lol. So i wonder if anyone knows who started this thing? why? anyone know?