On an--airplane,a spacecraft or a man-made satellite,there is usually an installed device called the "black box "Made of a special kind of material.it would remain unbroken,even if the entire craft were blown to pieces.The box records some important data,which provide clues as to what changes had occurred before the real thing came along and help to discover the causes of the disaster.     The black box.Therefore, becomes the last piece of evidence left.More often,it reveal a Schocking fact that many aircrafts met their disasters only because of a simple but fatal mistake Some hadn't been supplied with sufficient fuel;others crashed due to a bird flying in their paths.In many cases. the pilot had been tired.In 1986,the famous US space siadttle Challenger exploded soon after launch, because a screw on it was a bit loose! An idea thus occurs to me:if a human being was equipped with  _ , tracking allthe subtle inner Changes that had taken place over time,the results could astonish the world Newspapers carry no few such stories from day to day-cases of graft or bribe-taking ,how--innocent mail was robbed and killed, and so on.A fatal error, committed by a criminal at a particular point in his life,may have arisen from a small quarrel or out of envy.The number of those who were boom evil and deliberately sent themselves to the" gallows "is in fact extremely small.The disappointment towards the last moment of their life is no different from a  struggle against an aircraft crash!        Behave properly in small matters and take best care of the soul---this,I insist, is the message from that mysterious box planted deep inside human souls The purpose of the author is to
warn us of our safety tell us to treat others kindly how us his concerns remind us of taking good care of our soul