A cow does not know how much milk it has until the milkman starts working on it. Then it looks round in surprise and sees the pail full to the brim. In the same way a writer has no idea how much he has to say till his pen draws it out of him. Thoughts will then appear on the paper that he is amazed to find that he possessed. "How brilliant!" he says to himself. "I had no idea I was so intelligent." But the reader may not be so im pressed.