As the researches of Kroeber and Sorokin have conclusively shown...

As the researches of Kroeber and Sorokin have conclusively shown, "many great cultural or social systems or civilizations have many cycles, many social, intellectual, and political ups and downs in their virtually indefinitely long span of life, instead of just one life‑cycle, one period of blossoming, and one of decline." In the dynamics of intellectual and aesthetic creativity, Egyptian civilization rose and fell at least four times and Graeco‑Roman‑Byzantine culture, several times.

Similarly, China and India had two big creative impulses and the third has now surely begun. The Muslim civilization rose from the first/seventh to the fifth/eleventh century. Then it gradually declined till it received a deadly blow in the form of the Mongol onslaughts. Its chief monuments of…