Spengler thinks about why societies are failing.
A few choice paragraphs are excerpted below.

UPDATE: Mark Steyn’s christmas column covers similar ground.
UPDATE2: Wretchard recaps.

The world faces a danger more terrible than the worst Green imaginings. The European environmentalist who wants to shrink the world’s population to reduce carbon emissions will spend her declining years in misery, for there will not be enough Europeans alive a generation from now to pay for her pension and medical care. For the first time in world history, the birth rate of the whole developed world is well below replacement, and a significant part of it has passed the demographic point of no return.
But not only the religious need the hope of immortality. The most atheistic communist hopes that his memory will live on in the heart of a grateful proletariat. Even if we do not believe that our soul will have a place in heaven or that we shall be resurrected in the flesh, we nonetheless believe that something of ourselves will remain, in the form of progeny, memories, or consequences of actions, and that this something will persist as long as people who are like us continue to inhabit the Earth.
Human beings may not be the only animals who are sentient of death. (Elephants evidently grieve for their dead, and dogs mourn their dead masters.) But we are the only animals whose sense of continuity depends on culture as much as it does upon genes. Unlike men and women, healthy animals universally show an instinct for self-preservation and the propagation of their species. We do not observe cats deciding not to have kittens the better to pursue their careers as mousers.