What's the use of it?

But she followed them all the same. They came to where a crystal stream leapt over a little group of rocks. The dwarfs held their buckets under the cascade, and caught some drops. The drops turned into silver fish, each with a little loop on the end of its tail, all ready to hang on the tree.

They then took Hansi's pine cones and ferns and grasses, and even collected the frozen cobwebs from the bushes and let the spray from the waters fall on them, and lo and behold the most exquisite gems were ready for the decoration of the Christmas tree.

"You live at No 7, and you are seven years old," said the eldest of the dwarfs, addressing Hansi. ("However could he have known that?" she thought.) "Perhaps you can tell me what seven times seven makes?"

Hansi considered a moment. "No, we have not got so far as that in our arithmetic," she replied. "Twice seven is fourteen, that I know."

"Seven times seven is forty-nine and is the square of seven," said the dwarf. "Always remember that, for it is a most important fact in magic!"

Rummaging in his pocket, he took out a note-book and handed a leaf to her with this diagram and inscription on it

DIAGRAM

"Thank you very much," said Hansi, feeling duly impressed, and she never forgot this difficult fact in the multiplication table again, although she didn't quite understand the diagram, and in fact lost it on the way home.

The dwarfs set up the tree on a clear part of the path, and made a little stand for it of boughs cleverly intertwined and moss between. With many a hop, skip and jump of delight, they hung the silver fish and cones and nuts on it; the cobwebs spread themselves out all over the tree. Then they took red holly berries, and stuck them on the boughs where they turned into red candles. All red and silver was this loveliest of Christmas trees!

When it was finished, there was a momentary thrill, and they all cried "Ah!" in tones of wonder.

Then Hansi noticed that a noble herd of deer had approached; the gentle creatures were looking on with the deepest interest.