"He pointed to the light bulb as a clear demonstration of this concept. A light bulb does not have content in the way that a newspaper has articles or a television has programs, yet it is a medium that has a social effect; that is, a light bulb enables people to create spaces during nighttime that would otherwise be enveloped by darkness. He describes the light bulb as a medium without any content. McLuhan states that "a light bulb creates an environment by its mere presence."Likewise, the message of a newscast about a heinous crime may be less the individual news story itself — the content — and more the change in public attitude towards crime that the newscast engenders by the fact that such crimes are in effect being brought into the home to watch over dinner."
Federman (2004) What is the Meaning of The Medium is the Message? http://individual.utoronto.ca/markfederman/article_mediumisthemessage.htm^ Understanding Media