Among them, the sound smell refers to the understanding of Tao after hearing the sound, mainly the understanding of the four truths and sufferings.
Edge perception is a higher level than sound and smell. Buddhism is based on karma. Among them, there are twelve reasons to explain reincarnation: nameless fate, knowing fate, knowing fate, six colors, touching fate, love, taking love, taking life, being born and dying of old age. By understanding the twelve karma, enlightenment is karma.
However, there is no Tao in these two ways, only life and death, and there is no change between life and death. Only by practicing Mahayana Buddhism can we fundamentally achieve the nirvana vigilance of immortality.