Software is under a constant tension. Being symbolic it is arbitrarily perfectible; but also it is arbitrarily changeable.
One should forgive one's enemies, but not before they are hanged.
你说的话有什么益处呢?如果没有益处还要说,就是白费口舌。 
你无法回到过去改变开头,但你可以从现在开始改变结局。