In his biography about Tchaikovsky John Warrack points out that the ballet's greatest weakness is its story. It did not permit Tchaikovsky to musically develop the ballet in the manner of "Swan Lake" or "The Sleeping Beauty". What few symphonic passages exist in the ballet (mostly in Act 1) are not the best Tchaikovsky wrote. Warrack thinks that the "essential nature" of the ballet is found in the separate numbers. Tchaikovsky knew this when he put together the "Nutcracker Suite" to promote the complete ballet. Because the story was so weak and did not permit symphonic development, Tchaikovsky indulged his taste for "prettiness" in the separate numbers. This is what makes "The Nutcracker", according to Warrack, an "entertainment of genius".