By addressing that contemplating the mind is about the mind being neither self-generated nor other-generated, Chih-i demonstrates how truth can be realized through negation:

“In the case of empty space, if the mind that contemplates originates itself, then the mind does not need to rely on causes and conditions. Since the mind relies on causes and conditions, the mind has no power of self-generation. Since the mind has no power of self-generation, conditions cannot generate either. Since the mind and its condition have no [independent] existence, how can they be jointly substantial? If they cannot be obtained in conjunction, they cannot originate at all when they are in separation. If there is not even one single self-generation possible, how could there exist a hundred realms and a thousand dharmas? Because the mind is empty, everything that is created by the mind is empty. This emptiness is also empty. Such emptiness is not empty. Applying this Emptiness to the case of the Provisional, the Provisional is not provisional either. If there is neither Provisional nor Emptiness, it is ultimately pure and tranquil [the middle way].”

This passage stresses the significance of the mind contemplation. The method of contemplating the mind through negation is described as a way to realize the Middle Way-Ultimate Truth. By negating the mind that arises by its own or by another, one realizes the truth of Emptiness. By negating the substantiality of Emptiness and the Provisional, this prevents one from being attached to either of them, through which the truth as the Middle Way is realized. (Vol. 2, Page 82)