McLuhan’s excerpt focuses on how “the medium is the message”, with the message being effects on social or personal matters in human affairs. For instance, in his book he shows writing to be a medium for thought and bureaucracy; how it is juxtaposed across pages and pictures can communicate various feelings in deviating from how we normally read. He refers to electric light as “a medium without a message”, when it is not used to display words, and goes on to say that the content of any medium is another medium.
While I agree with much of his statement in how a message is not separate from the medium, I disagree with how broad this statement is when he refers to light in particular. I would argue that electric light can have an effect on mood and behavior by nature of color and intensity, which is are properties that belong almost solely to light. How we see color from other objects and mediums, such as paint, is because of light reflected back to us and how we evolved to perceive color. While perhaps colors associated with emotions might not be universal, blue light might give a feeling of coldness where red light might evoke heat and warmth, which can be considered psychic phenomena as well. In addition, a lack of light often leads us on a more universal scale to see a place as not as safe; a well-lit neighborhood at night is far less likely to be disturbed than a neighborhood that is dark and sporadically illuminated. Light conveys other messages that also affect our behavior on a greater scale, and while the medium of light is perhaps not light itself, but rather a consequence of our own thought process, it is similar to writing in that a greater meaning is imparted from our human experiences and thought processes.