Carl Jung: ....so the grown man shrinks back from the second half of life.

Just as the childish person shrinks back from the unknown in the world and in human existence, so the grown man shrinks back from the second half of life.

It is as if unknown and dangerous tasks awaited him, or as if he were threatened with sacrifices and losses which he does not wish to accept, or as if his life up to now seemed to him so fair and precious that he could not relinquish it.

Is it perhaps at bottom the fear of death?

That does not seem to me very probable, because as a rule death is still far in the distance and therefore somewhat abstract.

Experience shows us, rather, that the basic cause of all the difficulties of this transition is to be found in a deep-seated and peculiar change within the psyche. ~Carl Jung, CW 8, Para 777