In the next section, Master Dogen attempts to clarify in a very direct way just what type of conduct zazen is :
"...Therefore we should cease the intellectual work of studying sayings and chasing words. We should learn the backwards step of turning light and reflecting. Body and mind will naturally fall away, and the original features will manifest themselves before us. If we want to attain the matter of the ineffable, we should practice the matter of the ineffable at once."
Master Dogen was very concerned with 'sayings and words'; he compiled a big collection of Zen sayings or 'koans', and his voluminous philosophical masterpiece Shobogenzo contains thousands of words which are largely brilliant commentaries on Zen koans. In short, Master Dogen saw 'sayings and words' as very valuable and important. He is saying here though that the practice of zazen is a break from studying words and pursuing sayings and sorts of intentional mental activity.
'The backwards step' is a nice phrase that reminds me of how we sit down backwards on to the zafu (meditation cushion) before we turn to face the wall in zazen. It also suggests to me a type of retreat from our outwardly active world, the suspension of our usual activities and of our efforts to pursue goals or advance ourselves in the world.
'Turning light and reflecting' suggests the aspect of zazen where we become naturally more aware of our thoughts and feelings and all those things which are generally more concealed or underlying in our usual daily life: When we sit zazen for a while these things naturally, and without any great effort required, seem to arise to the surface. In zazen we can experience ourselves more clearly just as we might be able to discern our features clearly by looking in a mirror. Our attention is naturally reflected inwards.
'Body and mind will naturally fall away' describes the nice, balanced state of zazen where our thoughts and bodily perceptions just come and go unhindered when we stop involving ourselves with them by either grabbing onto them or rejecting them (trying to suppress them).
'The original features will manifest themselves before us' recalls themes from the Zen traditions like the popular old koan 'show me your original face before you were born'. It's an invitation to manifest the balanced state of zazen, to manifest our life, as it is before we manipulate it with thinking and any willful activities.
'If we want to attain the matter of the ineffable, we should practice the matter of the ineffable at once.' This last line has a strong whiff of the old Zen dialogues to it also; in one sense it doesn't make much sense and yet it seems to have a ring of truth to it. How can 'the ineffable' be a 'matter'? How can we possibly attain that which is ineffable? Surely you can't hold the ineffable in your hand or practice it without disappearing off the face of the Earth!?
This line comes from a wonderful saying by Master Tozan:
"If you want to attain the matter of the ineffable, you must have become someone of the ineffable. Now that you are already someone ineffable, why worry about attaining the matter of the ineffable?"
Buddhism holds that everything at this very moment is by nature already ineffable; all things material and immaterial constantly come and go from moment to moment in the endless dance of creation/ recreation. This allows for things to exist, to change, move and grow. A famous line from one of the most important Buddhist sutras (The Heart Sutra) reads: 'Form is emptiness, emptiness is form'. 'Attaining' this is to express it directly in zazen where we don't need to worry about attaining things as they already exist as they do (including us). Our body and mind, our perceptions and thoughts, naturally fall away of their own accord when we allow them to. In this way we can directly experience and learn the nature of ourselves and of everything.