Hagrid helped Harry on to the train that would take him back to the Dursleys, then handed him an envelope.
WAIT He has to go BACK to the Dursleys before he goes to school?? Fml that's so dumb, the adults really don't want him to have a chance in life! Why wouldn't they have waited until the closest possible time to get him out of the house, to diagon alley and hogwarts? Or just set him up with a room at the leaky cauldron???

