The three stages to taming the mind: quiet mind, empty mind and no-mind.

Quiet mind is full of its own quietness. Empty mind listens intently but still has a sense of self – of subject and object (something out there that it is listening out for). No-mind has no subject and no object, it embraces and contains everything.

When Dōgen said: Whoever told people that 'Mind' means thoughts, opinions, ideas, and concepts? Mind means trees, fence posts, tiles, and grasses. He was talking about no-mind.