Working on Mu

One of the few books about Zen that I recommend you is Zen Training: Methods and Philosophy by Katsuki Sekida, and I once already referred to the chapter 'Working on Mu', now you can reread it.

What is Mu? This is the first koan, and Sekida gives the answer: '"Mu" means "nothing"'. And he is right: there is no point to hide the answer since you have to prove your competence only to yourself; and the answer, I believe, should be even more specific because Mu is the basis on which the further practice is built.

Nothingness V.S. Emptiness

This is my comment on the article see the link below.

I doubt that for the author awareness is equivalent to understanding. Let me recall that when concentrating on the external world, you should also be fully aware of your body (see Zen Training : Methods and Philosophy by Katsuki Sekida.) Otherwise, no special skills are required, if you lose the feeling of your body while focusing on something. And you can really be aware of your body only by denying the outer world: the context (zazen in fact is a total denial of everything.) That's why spiritual practices have always attached great importance to such challenges as dousing with cold water, for example. Otherwise, you can easily concentrate on a sexual object and by doing this dissolve your self - to what elimination of dualism could this possibly refer?