Existentialism took root in the 19th century with Søren Kierkegaard and Friedrich Nietzsche, then flourished in mid-20th-century Europe — especially in France after the Second World War. Its guiding idea is that existence precedes essence: we are born without a fixed purpose and must define ourselves through our own free choices, bearing full responsibility in a universe that hands us no ready-made meaning. Jean-Paul Sartre and Simone de Beauvoir became its most public voices.