The Bodhisatta was once an ascetic. His dying words were, “Neither conscious nor unconscious.” His chief disciple explained that this statement meant sorrow can be found in both states and the only way to have true bliss is to strive toward insight, but the other disciples did not believe him. So the Bodhisatta came down from heaven and told them the chief disciple was wise and his explanation was correct. Then he returned to heaven.
In the Lifetime of the Buddha
The Bodhisatta’s chief disciple was an earlier birth of Sariputta, one of the Buddha’s top disciples. Sariputta was skilled at explaining things and after he had interpreted one of the Buddha’s lessons very clearly, the Buddha told this story so others knew Sariputta also had this ability in the past.