So Polly knew if she didn't take care and not get tired again, she
would be tucked into bed another fine day.

It was a long summer morning, and they were sailing up the Rhine, with
the delights of Brussels and Cologne behind them, and in between the
covers of the purple book, No. 4, Polly had been looking at ruined
castles and fortresses, at vine-clad terraces, and châlets, until she
turned to Grandpapa with a sigh.

"Tired, Polly, little woman?" he said, cuddling her up against him.

"No, not tired, Grandpapa," said Polly, "but, oh, there's so very much
of it over here in Europe."

"If you've found that out, you've learned the lesson early," said old
Mr. King, with a laugh. "As many times as I've been over here, there's
nothing that surprises me so much as the presumption with which we
travellers all rush about, expecting to compass all there is."

"But we ought to see everything," said Polly, "oughtn't we, Grandpapa,
when we've come so far to see it?" and she looked troubled.

"There's just where you are wrong, Polly, child," said old Mr. King.
"And this 'ought to see,' why, it's an old dragon, Polly, lying in wait
to destroy. Don't you let it get hold of you, but take my advice and
see only what you can make your own and remember. Then you've got it."