During the Hellenistic Age Greek culture transformed into an international civilization, forcing Greeks to broadened their polis-centered worldview. The conquests and policies of Alexander the Great mingled Greek and Near Eastern cultures. This process continued after Alexander's death and breakup of his empire into smaller kingdoms. Styling themselves divine monarchs in the Near Eastern manner, the Antigonid, Seleucid, and Ptolemaic kings built Greek-style cities and promoted Greek culture through a Macedonian and Greek ruling elite. These policies, as well as lively international trade, encouraged a cosmopolitanism that shaped every aspect of political, social, economic, and cultural life in the cities. Although cities controlled most of their own affairs, monarchy replaced the polis as the major political unit. Many Jews embraced Hellenism, but when the Seleucids tried to force Hellenization, the more orthodox rebelled, successfully reestablishing an independent Judea.

Hellenistic literature includes the lyrics of Callimachus, the epic of Apollonius of Rhodes, and the pastorals of Theocritus. Menander perfected New Comedy that concerned itself with everyday city life, and Polybius' history of Rome reflected Hellenistic universalism. Hellenistic artists turned from classical idealism to embrace realism, emphasizing the individual traits of both ordinary and prominent people. Monarchs and cities commissioned grand public works to glorify momentous deeds and events. Among the greatest Hellenistic achievements were in science. Working at the Athenian Lyceum, Theophrastus systematized biology and Strato developed experimental physics. In Alexandria, the most important Hellenistic city, physicians enlarged understanding of physiology and anatomy; Euclid synthesized previous developments in geometry; and Eratosthenes advanced the study of geography. Archimedes of Syracuse invented many ingenious devices and pioneered the science of hydrostatics.

Hellenistic philosophy continued the Greek rational tradition, but it addressed the needs of the age by stressing individual happiness in a complex world. In doing so it performed a quasi-religious function, thus preparing the way for Christianity. Epicureanism sought to alleviate individual anxiety and suffering by encouraging people to withdraw from public life, give up attachment to gods, and cultivate moderation in all things. Epicurus also opened philosophy to women, slaves, and barbarians, as did Zeno, the founder of Stoicism. The most influential of Hellenistic philosophies, Stoicism envisioned world-community of people bound by their shared possession of the Logos. Further, Stoicism built on Socrates' ideas by advocating individual moral improvement through reason. Skepticism rejected belief in a definite path to happiness. In its most sophisticated form, as represented by Carneades of Cyrene, Skepticism viewed all principles as hypotheses and held that morality should derive from experience rather than dogma. Adherents of Cynicism cultivated radical individualism, seeking happiness through ascetic detachment from human society.

During the Hellenistic Age, the mingling of western and eastern cultures forced Greeks to give up their parochial polis-centered worldview. In its place they developed a cosmopolitan, universalist outlook. That outlook ultimately achieved political expression in the Roman Empire and spiritual expression in Christianity.