It is a blank -- a real blank. It cannot be filled by a small trick or scant wit, which is probably the most difficult issue left for the next century.

• 我认为这是一个空白，一个实实在在的空白，填补这样的空白靠小聪明、小悟性是无法实现的。这也许是这个世纪留下的最大的难题。