The philosophy, culture, lifestyle, perspective, and attitude of liberalism were discovered and invented about 2600 years ago in the Athenian colony of Miletus. The philosophy of liberalism, in its essence, is the epistemology of reason and science, the ethics of individualism and self-interest, the politics of liberty and justice, the aesthetics of dynamism and heroism, and the spirituality of transcendence and triumph.
But from the beginning liberalism was opposed and attacked by its naturally-generated opposite, illiberalism. The ignorant, low, weak, and timid were usually anti-liberal. Their intellectual falsity and depravity took three forms: right-wing conservatism, left-wing progressivism, and down-wing nihilism.
The right-wingers tended to believe that the new, liberal version of "god" was the most important thing in the universe, and that the individuals's job was to live for his sake, and to nobly serve him as a kind of slave. The left-wingers tended to believe that the new, liberal version of "the collective" was the most important thing in the universe, and that the individuals's job was to live for their sake, and to nobly serve them as a kind of slave. The down-wing nihilists tended to believe that nothing was important or meaningful in the universe, and that the individual had no job or purpose in his trivial, meaningless, fundamentally-empty life. However, the up-wing liberals realized that the individual was the most important thing in the universe, and that his job, in the wonderful, new, liberal era, was to nobly live for his own sake, and try to be a kind of saint and hero, if not god.
Early conservatives could be found among the mystery cultists of Eleusis. Early progressives could be found among the communists of Sparta. Early nihilists were generally considerably evil, and thus tended to destroy themselves, and could only be found in temporary, scattered pockets. Early liberals could be found everywhere there were free, healthy, wealthy, successful, happy individuals, groups, and nations.
Up-wing liberal Greeks like Aristotle, Epicurus, and Zeno the Stoic, along with up-wing liberal Romans like Cicero, Lucretius, and Horace, radically enhanced Western society and personal happiness in almost every way. But right-wing conservatives, with assistance from their mutually illiberal allies on the left, heavily defeated liberal ideas and ideals, and caused a Dark Age to descend upon the West in the Medieval period. Eventually, however, new liberals emerged during the Renaissance and Enlightenment, such as Locke, Smith, Voltaire, and Jefferson. But left-wing progressives, with assistance from their mutually illiberal allies on the right, caused the current Dark Age to descend upon the West in the Postmodern period.
Now, new up-wing liberals like the Austrian economists, political libertarians, and philosophical Objectivists, have prominently emerged over the past half-century. And so since about the 1980s, the philosophy, culture, lifestyle, perspective, and attitude of liberalism have been rising.