Like a River

An old zen master was on his dieing bed, surrounded by his disciples. He prepared to speak and everybody waited in silence.

He said: After years of investigation, I can certainly tell you that wisdom is like a river.

After a minute, one student broke the silence and asked: Master, forgive me, but what does that mean "wisdom is like a river"?

Ok, the master said - it's not like a river.

Then he died.