Now, after a while, the Foster-mother had to go on another journey; and, before she went, she forbade the Lassie to go into those two rooms into which she had never been. She promised to beware; but when she was left alone, she began to think and to wonder what there could be in the second room, and at last she could not help setting the door a little ajar, just to peep in, when – Pop ! out flew the Moon.
~ from The Lassie & Her Godmother
(East of the Sun & West of the Moon: Old Tales from the North)