Zen Mind, Beginner's Mind: Informal Talks on Zen Meditation and Practice

Instead of having some particular object in mind, you should limit your activity. When your mind is wandering about elsewhere you have no chance to express yourself. But if you limit your activity to what you can do just now, in this moment, then you can express fully your true nature, which is the universal Buddha nature. This is our way.

Zen mind is one of those enigmatic phrases used by Zen teachers to make you notice yourself, to go beyond the words and wonder what your own mind and being are. This is the purpose of all Zen teaching—to make you wonder and to answer that wondering with the deepest expression of your own nature.