The natural real buddha nature is always inherently complete and luminous; it was thus before our parents gave birth to us, it is thus right now, and it will always be thus forever.
Originally there is not a single thing. Since there's not a single thing, what is to be called original? If you can see into this, you will save the most mental energy.
When divergent thoughts arise, adamantly cut them off yourself. This is expediently called concentration and insight, but it is not a reality; this mind itself is inherently concentrated and inherently insightful.
Huang-po said, "This mind is always intrinsically round and bright, illuminating everywhere. People of the world don't know it, and just recognize perception and cognition as mind. Empty perception and cognition, and the road of the mind comes to an end." He also said, "If you want to know the mind, it is not apart from perception and cognition; and yet the original mind does not belong to perception and cognition either."
When you come to this, it is really essential for you to look into yourself; it is not a matter of verbal explanation. The more the talk, the further removed from the way. Those who are successful at introspection know for themselves when the time comes and do not need to ask anyone--all false imaginations and emotional thoughts naturally disappear. This is the effect of learning the way.
A thousand falsehoods do not compare to a single truth. If you are not thus, even if you consciously apply your mind, seeking effectiveness daily, it is all in the realm of impermanence, becoming and passing away. A master teacher said, "If you want to cultivate practice and seek to become a buddha, I don't know where you will try to seek the real." If you can see reality within the mind spontaneously, having reality is the basis of attaining buddhahood. If you seek Buddha externally without seeing your own essential nature, you are an utter ignoramus.