Once upon a time a king gathered some blind men about an elephant and asked them to tell him what an elephant was like. The first man felt a tusk and said an elephant was like a giant carrot; another happened to touch an ear and said it was like a big fan; another touched its trunk and said it was like a pestle; still another, who happened to feel its leg, said it was like a mortar; and another, who grasped its tail said it was like a rope. Not one of them was able to tell the king the elephant's real form.
In like manner, one might partially describe the nature of man but would not be able to describe the true nature of a human being, the Buddha-nature.
There is only one possible way by which the everlasting nature of man, his Buddha-nature, that can not be disturbed by worldly desires or destroyed by death, can be realized, and that is by the Buddha and the Buddha's noble teaching.