What each man does is based not on direct and certain knowledge, but on pictures made by himself or given to him…. The way in which the world is imagined determines at any particular moment what men will do.

Walter Lippmann developed this idea in the early 1920s while analyzing how modern mass society forms political judgments under conditions of complexity and limited firsthand experience. Writing in the wake of World War I—when propaganda, censorship, and the rapid growth of newspapers and other mass media had demonstrated how public opinion could be shaped—Lippmann argued that citizens typically respond not to “the environment” directly but to mental representations of it. His broader project in this period was to explain why democratic publics so often act on partial, mediated information, and why the manufacture and circulation of images, stereotypes, and narratives becomes politically decisive.

The quote states Lippmann’s core claim that human action is guided less by verified knowledge than by “pictures” in the mind—models, stereotypes, and narratives assembled from personal experience and social communication. Because the world is too vast and intricate to grasp directly, people simplify it into an imagined version that feels coherent and actionable. The political implication is that whoever influences these pictures—through media framing, propaganda, education, or cultural myth—can influence behavior. Lippmann is not merely calling people irrational; he is diagnosing a structural limitation of perception in modern life, where mediated images often stand in for reality and thereby steer collective decisions.