One day John and Mary took a walk with their father. It was a very warm, sultry day, and far up in the sky were many clouds.

"Just look," said John, "what big clouds!"

Oh, yes," said Mary; "I wonder what the Lord has made the clouds for?"

"The clouds are very useful," said the father. "The Lord has made them because He loves us. The clouds are large curtains."

"Curtains?" exclaimed the children, astonished. "Yes, truly," answered the father; "don't you know what we use curtains for?"

"Oh, yes," said Mary, "I know. When the sun shines too strongly we draw the curtain to keep off the heat."