other media, move to a second stage in which something is obsolesced.

McLuhan: By the way, they are simultaneous, they are not sequential. But . . . it’s handy to use sequence. But these four aspects are simultaneous in every case. They also form a metaphor; they are a four-part metaphor; A is to B as C is to D; they are in ratio. This was not intended. It was only after some time I discovered that these four things were metaphors. By the way, this right hemisphere thing is called metaphoric, as opposed to scientific. The quantified measurable side, left hemisphere, is called scientific because it is quantifiable, whereas the other one is called metaphoric because you can’t quantify it. But, the four divisions in these little tetrads are simultaneous and, in their relation to each other, they form a metaphor. Now