The first time I heard about Sun Tsu, the art of war I was made to understand that this four thousand year old chinese book could be read in many ways. The most obvious way to read it, is of course, to read it as a book abput warfare. The art of war, how to succesfully wage war in the Chinese middle ages.
On a deeper level, of course, the art of war is about strategy in general and supoaedly, many of the strategic lessons of the book are applicable outside the context of the chinese middle ages and even outside the context of warfare. Some business schools use the text.
However the first time I heard about the multi levelness of The art of war, I understood this in a different way. I thought that it was a feature of the Chinese way of writing that was cleverly exploitet by master Sun or his disciples. That you could map the characters in the text to a different set of meanings and thereby changing the meaning of the text, but not the meaning of the underlying wisdom.