"Everything she saw around her was so beautiful and so alive that Sophie had to rub her eyes to really believe it. But nothing she was looking at now would last. And yet- in a hundred years the same flowers and the same animals would be here again. Even if every single flower and every single animal should fade away and be forgotten, there would be something that "recollected" how it all looked.
Sophie gazed out into the world. Suddenly a squirrel ran up the trunk of a pine tree. It circled the trunk a few times and disappeared into the branches.
"I've seen you before!" thought Sophie. She realized that maybe it was not the same squirrel that she had seen previously, but that she had seen the same "form." For all she knew, Plato could have been right. Maybe she really had seen the eternal "squirrel" before- in the world of ideas, before her soul had taken residence in a human body.
Could it be true that she had lived before? Had her soul existed before it got in a body to move around in? And was it really true that she carried a little golden nugget inside her- a jewel that cannot be corroded by time, a soul that would live on when her body grew old and died?"
-Jostein Gaarder, Sophie's World