You should understand that birth-and-death is itself nirvana. Nirvana is not realized outside of birth-and death. - Dōgen

The zazen I speak of is not learning meditation. It is simply the Dharma gate of repose and bliss, the practice-realization of totally culminated enlightenment. It is the manifestation of ultimate reality. Traps and snares can never reach it. Once its heart is grasped, you are like the dragon when he gains the water, like the tiger when she enters the mountain. For you must know that just there (in zazen) the right Dharma is manifesting itself and that, from the first, dullness and distraction are struck aside.

春は花
夏ほととぎす
秋は月
冬雪さえて
すずしかりけり

You should stop searching for phrases and chasing after words. Take the backward step and turn the light inward. Your body-mind of itself will drop off and your original face will appear. If you want to attain just this, immediately practice just this.