5 ideas
To study the Buddha way is to study the self; to study the self is to forget the self; to forget the self is to be actualized by the myriad things. Close examination of the self does not turn up a fixed owner of experience. It removes the habit of treating one's viewpoint as the centre, so that things show up on their own terms and not as objects arranged around a subject.
In Genjōkōan, Dōgen describes a person on a boat who looks at the shore and thinks the shore is moving. When he looks closely at the boat itself, he sees that the boat is what moves. In the same way, confused perception of body and mind leads people to think their own self is permanent while the world changes.
Dōgen rejects the model in which practice is a means and enlightenment is a later result. Seated meditation (zazen) is itself the full expression of realization, so practice has no finish line where it becomes unnecessary. Treating practice as instrumental keeps the practitioner grasping for a future goal. That grasping is exactly the obstacle to realization.
Firewood does not turn into ash in the sense of one thing moving along a line. Firewood abides in its own dharma-position with its own before and after, and ash abides in its own. Seeing each moment as complete in itself, not as a stage in a transition, dissolves the anxious story of life becoming death. Each is a full situation in its own right.
In the Uji fascicle, Dōgen argues that beings do not exist inside a container of time. Being and time are the same thing: each existent is a time, and each time is an existent. The present moment is not a passing slice between past and future. It contains its full reality, so how you inhabit each moment is the whole of your existence.