In my lifetime I was to write only one book, this would be...

In my lifetime I was to write only one book, this would be the one. Just as the past Lingers in the present, all my writings after night, including those that deal with biblical, Talmudic, or Hasidic themes, profoundly bear it's stamp, and cannot be understood if one has not read this very first of my works. Why did I write it? Did I write it so as not to go mad or, on the contrary, to go mad in order to understand the nature of the madness, the immense, terrifying madness that had erupted in history and in the conscience of mankind?