The book is the Decline of the West by Oswald Spengler, which was published from 1918-1923 in two volumes. Spengler's been attacked for his anti-scientific approach to history, although most of that comes from the Positivist and neo-Kantian crowd.

Here are a few passages from Wikipedia which caught my attention. Important parts are underlined:
 

The book introduces itself as a "Copernican overturning" operating as a paradigm shift involving the rejection of the Eurocentric view of history, especially the division of history into the linear "ancient-medieval-modern" rubric. According to Spengler, the meaningful units for history are not epochs but whole cultures which evolve as organisms. He recognizes eight high cultures: Babylonian, Egyptian, Chinese, Indian, Mexican (Mayan/Aztec), Classical (Greek/Roman), Arabian, Western or "European-American." Cultures have a lifespan of about a thousand years. The final stage of each culture is, in his word use, a 'civilization'.

Spengler also presents the idea of Muslims, Jews and Christians, as well as their Persian and Semitic forebears, being Magian; Mediterranean cultures of the antiquity such as Ancient Greece and Rome being Apollonian; and the modern Westerners being Faustian.

Apollonian Civilisation is focused around Ancient Greece and Rome. Spengler saw its world view as being characterised by appreciation for the beauty of the human body, and a preference for the local and the present moment.

Magian Civilisation includes the Jews from about 400BC, early Christians and various Arabian religions up to and including Islam. Its world feeling revolved around the concept of world as cavern, epitomised by the domed Mosque, and a preoccupation with essence. Spengler saw the development of this civilisation as being distorted by a too influential presence of older cultures, the initial vigorous expansionary impulses of Islam being in part a reaction against this.

Faustian Civilisation began in Western Europe around the 10th century and according to Spengler such has been its expansionary power that by the 20th century it was covering the entire earth, with only a few Regions where Islam provides an alternative world view. The world feeling of Faustian civilisation is inspired by the concept of infinitely wide and profound space, the yearning towards distance and infinity.

Spengler divides the concepts of culture and civilization, the former focused inward and growing, the latter outward and merely expanding. However, he sees Civilization as the destiny of every Culture. The transition is not a matter of choice—it is not the conscious will of individuals, classes, or peoples that decides. Whereas Cultures are "things-becoming", Civilizations are the "thing-become." As the conclusion of a Culture's arc of growth, Civilizations are outwardly focused, and in that sense artificial or insincere. Civilizations are what Cultures become when they are no longer creative and growing. For example, Spengler points to the Greeks and Romans, saying that the imaginative Greek culture declined into wholly practical Roman civilization.

Decline is also evidenced by a formlessness of political institutions within a state. As the "proper" form dissolves, increasingly authoritarian leaders arise, signaling decline. The first step toward formlessness Spengler designates Napoleonism. A new leader assumes powers and creates a new state-structure without reference to "self-evident" bases for governance. The new régime is thus accidental rather than traditional and experienced, and relies not on a trained minority but on the chance of an adequate successor. Spengler argues that those states with continuous traditions of governance have been immensely more successful than those that have rejected tradition. Spengler posits a two-century or more transitional period between two states of decline: Napoleonism and Caesarism. The formlessness introduced by the first contributes to the rise of the latter.

Spengler predicts that permanent mass-conscription armies will be replaced by smaller professional volunteer armies. Army sizes will drop from millions to hundreds of thousands. However, the professional armies will not be for deterrence, but for waging war. Spengler states that they will precipitate wars upon which whole continents—India, China, South Africa, Russia, Islam—will be staked. The great powers will dispose of smaller states, which will come to be viewed merely as means to an end. This period in Civilizational decline he labels the period of Contending States.

Caesarism is essentially the death of the spirit that originally animated a nation and its institutions. It is marked by a government which is formless irrespective of its de jure constitutional structure. The antique forms are dead, despite the careful maintenance of the institutions; those institutions now have no meaning or weight. The only aspect of governance is the personal power exercised by the Caesar. This marks the beginning of the Imperial Age.

Despite having fought wars for democracy and rights during the period of Contending States, the populace can no longer be moved to use those rights. People cease to take part in elections, and the most-qualified people remove themselves from the political process. This marks the end of great politics. Only private history, private politics, and private ambitions rule at this point. The wars are private wars, "more fearful than any State wars because they are formless". The imperial peace involves private renunciation of war on the part of the immense majority, but conversely requires submission to that minority which has not renounced war. The world peace that began in a wish for universal reconciliation ends in passivity in the face of misfortune, as long as it only affects one's neighbor. In personal politics the struggle becomes not for principles but for executive power. Even popular revolutions are no exception: the methods of governing are not significantly altered, the position of the governed remains the same, and the strong few determined to rule remain atop the rest of humanity.

Democracy and plutocracy are equivalent in Spengler's argument. The "tragic comedy of the world-improvers and freedom-teachers" is that they are simply assisting money to be more effective. The principles of equality, natural rights, universal suffrage, and freedom of the press are all disguises for class war (the bourgeois against the aristocracy). Freedom, to Spengler, is a negative concept, simply entailing the repudiation of any tradition. In reality, freedom of the press requires money, and entails ownership, thus serving money at the end.