Book excerpt: A watershed event in the field of sociology, this text introduced “a major breakthrough in the sociology of knowledge and sociological theory generally” (George Simpson, American Sociological Review). In this seminal book, Peter L. Berger and Thomas Luckmann examine how knowledge forms and how it is preserved and altered within a society. Unlike earlier theorists and philosophers, Berger and Luckmann go beyond intellectual history and focus on commonsense, everyday knowledge—the proverbs, morals, values, and beliefs shared among ordinary people. When first published in 1966, this systematic, theoretical treatise introduced the term social construction,effectively creating a new thought and transforming Western philosophy.