David now found himself able to understand the song of the Blue Bird as he had never understood it before; for he could now perceive the inside of things as well as the outside. He was much surprised when he realized that, instead of its being just a bird’s song as he had always supposed, each note meant certain definite ideas and thoughts which the Blue Bird was expressing. For this reason the song was never twice exactly alike. David had never noticed this before: the song had always seemed to him just the same clear, sweet musical ripple, repeating itself over and over. Now he began to detect the several notes and how varied they were in accent and arrangement; and he learned that it was within this variety of accent and arrangement that the sense of the song was to be found. Then, little by little, David caught the inner meanings of the different symbols of sound; so that, from now on, every time the Blue Bird sang, its song conveyed a special message to David’s heart and mind. He had followed the Bird for some time--just how long, he did not know--when presently he came upon a tiny green rose-covered cottage. The Bird flew to the vine over the doorway and began to sing as if its tiny throat would burst. “Knock on the door, knock on the door! Here lives the good woman you once met before.” David walked up to the door and knocked fearlessly. In a moment it opened; and there before him stood the dear little white-haired old woman whom he had met in the woods. “David!” she cried in delight. “David! why, is it really you? Have you come at last? I have been looking for you this long time. So you did see the Blue Bird after all, and you did follow it. I know that you followed it; else you never could have found your way here. One never reaches this house in any other way, for this, you know, is the Mansion of Happiness. Come in,” she added. “You are welcome!” “Is this really the Mansion of Happiness?” asked David. “I have heard of it before: we used to play a game called ‘The Mansion of Happiness.’ But I never knew there was a real place of that name.” “Yes, there is a real place of that name, David, and this is it.” “Well,” said David, “then I should like to spend the rest of my life right here.” “No, you wouldn’t, either,” said the old woman. She spoke so abruptly that she almost startled David. “Why not?” said he. “Because you would tire of it.” “Why?” “Because you are a living Soul,” said the old woman, “and a living Soul always tires of a thing in time.” “Why?” asked David. “Because if it didn’t, and were perfectly satisfied, it would know no progress. It is dissatisfaction caused by growing tired of a thing, or the growing tired of a thing causing dissatisfaction, that makes one desire and seek something else. It is this desire and seeking that is the root of all progress.” David found it hard to understand her very well; her words seemed strange to him. So he just said, “Why?”