In surgery(外科，手术室),there is a red line on the floor,that marks the point where the hospital goes from being accessable to be of limits to all but special few,crossing the line under off the rise is not policy(未经许可不允许过那道线:Without permission not allowed to pass). In general,lines are there for a reason,for safty,for security,for quiet(安静,和平：peace).If you choose to cross the line,you pay too much to do so as you are on rest(这样做太冒险了).So why is it that the bigger the line the greater the temptation to cross it. 

    We can't help ourselves,we see a line,we want to cross it,maybe it's the through of trading the familer from the unfamiler,a sort of(一种；有点) personal dare.only problem is,once you cross it,it's almost impossible to go back.But,if you do manage to make it back to cross that line,you find safty and numbs.