TO SEE THE MENU HOW DECLINE OF THE WEST REALLY GOT UNDER WAY

you have to look at the Reformation, and move fitfully forward.

In the later decline period, say during the 18th Century, call it The Enlightenment, one has to glance then at the Enlightenment's crowning achievement, the French Revolution, but also pay attention in passing to earlier revolutionary and post Reformation middle decline period antecedents in Britain.

Finally, to get a full flavor of decline, now in full flood, one has to study the British Isles example of a slow, but sure, final and irrevocable slide into party liberalism; but also, strikingly, into an insipid repellent species of conservatism opposing it, at the same time. 

John Vincent's book, The Formation of the British Liberal Party, seems a good place to sample this late, piquant, frothy dish in all its steamy, fetid, marinated repugnance.