Only when morality, meditative concentration, and wisdom are complete can the bottom of the bucket fall out.

In the past, Chan practitioners who investigated Chan and, upon finding the eighth consciousness, attained enlightenment would say that "the bottom of the bucket has dropped out." What is the bucket? In the Śūraṅgama Sūtra, the Buddha compares the human body to a flesh-bucket, shaped like a bucket. And sentient beings take this flesh-bucket as themselves, as a truly existing, imperishable self.

When a Chan practitioner awakens to the eighth consciousness, he knows that the eighth consciousness is real, never ceasing to exist, the true self; the five-aggregate body is merely a false shell manifested by the eighth consciousness, not real, not the self, yet also not different from the self that is the eighth consciousness. In this way, he no longer takes the five aggregates as the self, negates the flesh-bucket of the five-aggregate body, and lays down the heavy burden of the five aggregates. At this point, both body and mind are empty, and there is incomparable tranquility (praśama)—this is likened to the bottom of the bucket dropping out.

The prerequisites for the bottom of the bucket dropping out are: precepts, meditative concentration (samādhi), and wisdom must be complete; merit must be complete; the bodhisattva's six perfections must have been fully cultivated; and the provisions for entering the Path must also be complete. Only when the conditions of time and circumstance ripen can the bottom of the bucket drop out. At this time, one also simultaneously attains the first fruit of the Small Vehicle, severing the three fetters, and will never again fall into the three evil destinies.

Because the first fruit of the Small Vehicle is the realization that the five aggregates and eighteen realms are suffering, empty, impermanent, and non-self, when one awakens to the eighth consciousness, one also knows that the five aggregates and eighteen realms are not the self—they are illusory, empty and unreal, not real. Therefore, attaining the fruit of the Great Vehicle simultaneously attains the fruit of the Small Vehicle; but attaining the fruit of the Small Vehicle does not necessarily mean one can attain the fruit of the Great Vehicle. This is the principle by which the Great Vehicle dharma encompasses the Small Vehicle dharma.