Enlightenment has no definite form or nature by which it can manifest itself;
so in Enlightenment itself, there is nothing to be Enlightened. Enlightenment
exists solely because of delusion and ignorance; if they disappear, so will
Enlightenment. And the opposite is true also: there is no Enlightenment apart
from delusion and
ignorance; no delusion and ignorance apart from Enlightenment. Therefore, be on guard against thinking of Enlightenment as a "thing" to be grasped at, lest it, too, should become an obstruction. When the mind that was in darkness become Enlightened, it passes away, and with its passing, the thing which we call Enlightenment passes also. As long as people desire Enlightenment and grasp after it, it means that delusion is still with them; therefore, they who are following the way to Enlightenment must not grasp at it, and if they reach Enlightenment, they must not linger in it. When people attain Enlightenment in this sense, it means that everything is Enlightenment itself as it is; therefore, people should follow the path to Enlightenment until in their thoughts, worldly passions and Enlightenment become identical as they are. This concept of universal oneness - that things in their essential nature have no distinguishing marks - is called Emptiness. Emptiness means non-substantiality, the unborn, having no self-nature, no duality. It is because things in themselves have no form or characteristics that we can speak of them as neither being born nor being destroyed. There is nothing about the essential nature of things that can be described in terms of discrimination; that is why things are called non-substantial. As has been pointed out, all things ap- pear and disappear because of causes and condition. Nothing ever exists entirely alone; everything is in relation to everything else. Wherever there is light, there is shadow; wherever there is length, there is shortness; wherever there is white, there is black. Just like these, as the self-nature of things cannot exist alone, the are called non-substantial. By the same reasoning, Enlightenment cannot exist apart from ignorance, nor ignorance apart from Enlightenment. Since things do not differ in their essential nature, there can be no duality. It is a mistake for people to seek a thing supposed to be good and right and to flee from another supposed to be bad and evil. If people insist that all things are empty and transitory, it is as great a mistake as to insist that things are real and do not change. If people become attached to a self, it is a mistake because it cannot save them from suffering.
If they believe that there is no self, it is also a mistake and it would be useless for them to practice the Way of Truth. If people assert that everything is suffering, it is also a mistake; if they assert that everything is happiness, that is a mistake, too. All duality merges in the Middle Way.