Prabhupada: So it may..., it can be taken figuratively, that when one forgets his position, that is a kind of death also. One forgets himself. But actually soul is eternal, and what Augustine says as spiritual death, that is his forgetfulness. Just like in unconsciousness one forgets his identity, but if he is dead then he cannot revive consciousness. Similarly, it is little difficult for the bodily concept of life persons, but there are many proofs and understanding that soul is eternal. He, of course, until he gets his freedom from this material existence, he is spiritually dead. Even though he is working in this material form, because he has forgotten his real identity, that is also a kind of death. Ya nisa sarva-bhutanam tasyam jagarti samyami. This sloka explains how one is dead and how one is alive. When one is forgetful of his spiritual consciousness, God consciousness, he is supposed to be dead, and when he, one is alive to the spiritual consciousness or God consciousness, he is alive. In this sense, it is a question of two stages, awakening stage and forgetful stage, but actually a soul is eternal. He never dies, even after the annihilation of this body.
Hayagriva: But the forgetful stage is never everlasting or eternal, is it?
Prabhupada: Yes, it is not. It can be, what is called, revived, his consciousness. That is our Krsna consciousness movement. Just like a man is sleeping, almost unconscious, but if you call him again and again, and the sound enters through the ear into the heart, he becomes awakened. Similarly, by this chanting process he revives his spiritual consciousness, then he is alive in his spiritual life.
[Srila Prabhupada, * Discussions with Hayagriva dasa, St. Augustine]