Western Civilization begins in the Mediterranean (Greece, the Middle East, Rome), advances through Western Europe, and now penetrates or impacts nearly everywhere on Earth in terms of modern lifestyles of individual rights, urbanization, and lifespan extension, and economies devoted to material improvement, intensive exploitation of nature, and population growth.
Western Civilization develops from many sources, and different participants identity with different traditions, but two main sources & continuing strands prevail:
1a. modern science and engineering (biology, medicine, geometry, logic, math, metaphysics, physics, architecture)
1b. modern government, lifestyles and art
government: democracy, courts, study of ethics, philosophy, meritocracy
sports: Olympics, marathon running
art: sculpture, architecture
literature: epic poetry, drama (comedy and tragedy), rhetoric, literary theory
2b. moral codes and values (10 Commandments, Golden Rule, sovereignty of human life over nature, equality of human souls)
2c. family structures (esp. patriarchal nuclear family + mobility: ancient Jews as nomads, Americans as mobile society)
2d. tribal identities? (churches, temples, mosques, etc. as centers of ethnic identities and ideologies)
The two strands may not appear multicultural but both variously succeed in converting, penetrating, or traversing other peoples or cultures.
In New World or American culture, these two strands are particularly varied by the African Diaspora and Native America.
For the sake of literary studies, a shared reason for these two cultures' dominance in Western Civilization:
Record-keeping, so that data and learning can be preserved beyond the limits of human speech.
Maintenance of readers and writers to preserve and promote those records.
For instance . . .
The Jews of the Bible's Old Testament were serious record-keepers and preserved their writings in the Arc of the Covenant and beyond; Christian scriptures and commentaries were translated from Greek to Latin to European languages and beyond.
Greek civilization and its many texts and records rose and fell, but Greek peoples became the teachers, scholars, scientists, and engineers of the Mediterranean world. Roman civilization and literature inherited much from the Greeks and, through the Catholic Church, transmitted it to Europe, whence it spread to the Americas and beyond.
This account of Western Civilization neglects the ancient or
classical writings of Islam, Buddhism, and other religions or civilizations
across the earth, which can be accounted as additional influences.