Dogen also instructed,
The primary point you should attend to is detaching yourself from personal views. To detach yourself from personal views means to not cling to your body. Even if you have thoroughly studied the words and stories of the ancient masters and have been practicing zazen continuously and immovably like iron or rock, if you cling to your body and do not detach yourself from it you will be unable to attain the Way of the buddhas and patriarchs in ten thousand aeons or a thousand lifetimes.
Even though you think you may have realized the provisional teachings and the true teachings or the authentic Exoteric and Esoteric scriptures, if you have not detached from the mind which clings to your body, it is like vainly counting another’s wealth without possessing even a half-penny of your own. I implore you to sit quietly and seek the beginning and the end of this body on the ground of reality. Your body, hair, and skin, were originally comprised of the two droplets from your father and mother. Once the breath stops, they scatter and finally turn into mud and soil on the mountains and fields. How can you cling to your body? Moreover, looking at your body from the basis of the dharma, which among the gathering and scattering of the eighteen elements1 can you identify as your body? There are differences between the teaching schools and those other than the teaching schools (Zen)2. However, they both show the ungraspability of the body from beginning to end and assert egolessness as the essential point in practicing the Way. If you first realize this reality, the true Buddha-Way will manifest itself clearly.