When a civilisation declines it goes into reverse with all the wealth, power and wisdom realised by its rise being discarded at an ever increasing rate until dissolution. The people will discover that:
Tyranny and injustice will reign as delusion triumphs while the community loses its racial identity and dissolves into impotence. But this will never be generally recognized because the source of the disease is the waning of citizens' comprehension. A decay made obvious by the disappearance of plain speaking.
Such a society is no longer engaged in creating a human heaven on earth, but is earnestly constructing the very opposite where:
However this will always be denied because truth will be vanquished by lies.
(see a letter from South Africa for a simple example of decline).