information:classification
Understanding Media (1964)

McLuhan's best-known work, Understanding Media: The Extensions of Man (1964), is a seminal study in media theory. Dismayed by the way in which people approach and use new media such as television, McLuhan famously argues that in the modern world "we live mythically and integrally…but continue to think in the old, fragmented space and time patterns of the pre-electric age."

McLuhan proposes that media themselves, not the content they carry, should be the focus of study—popularly quoted as "the medium is the message". His insight is that a medium affects the society in which it plays a role not by the content it delivers, but by its own characteristics. McLuhan points to the light bulb as a clear demonstration of this. A light bulb does not have content in the way that a newspaper has articles, or a television has programs, but it is a medium that has a social effect; that is, a light bulb enables people to create spaces at night that would otherwise be enveloped by darkness. He describes the light bulb as a medium without any content. McLuhan writes, "a light bulb creates an environment by its mere presence." More controversially, he postulates that content has little effect on society—for example, whether television broadcasts children's shows or violent programming, its effect on society is identical. He notes that all media have characteristics that engage the viewer in different ways; for instance, a passage in a book can be reread at will, but a movie must be screened again in its entirety to study any part of it.