E. Nesbit 
The Magic City 

Philip Haldane and his sister lived in a little red-roofed house in a little red-roofed town. They had a little garden and a little balcony, and a little stable with a little pony in it-and a little cart for the pony to draw; a little canary hung in a little cage in the little bow-window, and the neat little servant kept everything as bright and clean as a little new pin.
Philip had no one but his sister, and she had no one but Philip. Their parents were dead, and Helen, who was twenty years older than Philip and was really his half-sister, was all the mother he had ever known. And he had never envied other boys their mothers, because Helen was so kind and clever and dear. She gave up almost all her time to him; she taught him all the lessons he learned; she played with him, inventing the most wonderful new games and adventures. So that every morning when Philip woke he knew that he was waking to a new day of joyous and interesting happenings. And this went on till Philip was ten years old, and he had no least shadow of a doubt that it would go on for ever. The beginning of the change came one day when he and Helen had gone for a picnic to the wood where the waterfall was, and as they were driving back behind the stout old pony, who was so good and quiet that Philip was allowed to drive it. They were coming up the last lane before the turning where their house was, and Helen said:
‘To-morrow we’ll weed the aster bed and have tea in the garden.’