All cultures come to a Civilization phase, an autumn when this breaks down. Mega-cities are characteristic of this time. Politics is motivated by money, and move through Imperialism and the Period of Contending States to Caesarism, a period of despots. Science no longer reaches certainties. People no longer accept common principles or goals, they fight all rules from the past. The arts, rather than working in ways that seem obvious to the artists and the people, follow fashions with constant changes of style. Later in this culture after a period of atheism, people turn to a religious renewal based on the religion developed in the spring of the culture.
Spengler sees our culture as having finished its summer in about 1800--1770 in literature and with Wagner in music. He views developments in all the arts as evidence of decadence. His advice to those living in the Civilization phase is to look for the direction of movement and contribute positively to it--the Civilization will move in the direction of its Destiny, regardless of our choices. We can choose to contribute or to have no impact.