I have read this book translated by Prof. Tadashi Isoyama. A very interesting work on the last 4 years of Mozart's life.
It has been widely believed that Mozart spent hard time in his last years of life. The movie "Amadeus" typically expresses such a view on his life. He had suffered from debts, poverty and an illness led him to death. However, the author of this work tells us it is wrong.
In the last 4 years of his life, Mozart has gained a position at the court of Austrian Empire, which he had yearned for. Since this epoch making event for him, he has opened up the new horizon for new style and perspective of music in his composing activity. He takes the example of such music in the Magic Flute, the piano sonata KV533, Requiem or the ｆｒａｇｍｅｎｔａｒｙ musics as listed in the 6th chapter of this book. You may listen those fragments in the site linked here. They are revolutionary works which lead us to the new horizon Mozart had headed to. The title of this book "Mozart at the Gateway to the Fortune" tells us what the author thought of.
There are a lot of fragments of composition by him left in the history. Mozart used to answer to his father asking him to compose quicker that he had finished composing music but only had to write it down on paper. When it became necessary for him to do so, all he should do was to recall all the music in his memory and write it down. The author tells that the existence of those fragmentary musics means there the music opening the gate to new horizon has been playing in his mind. It is the enthusiasm for new style of music more profound and rich with polyphony and chord. It has just a start for revolutionary music.
I was taught that my view on his last years of life was totally wrong. We should listen to his latest music as the gate to the new fortune in his music. However, in other words, his death has deprived us of the rich new world of his music all of sudden. it has been lost in the eternal nihility. It seems another aspect of a reality shown in this history.
The world and our lives are incomplete. The more we feel lost due to that incompleteness in our lives, the more valuable Mozart's music in the latest years of his life sound to us.