The medium is the message, except when it isn’t.
When Mao famously said that power springs from the barrel of a gun, it was assumed that he was talking about guns. There wasn’t much interest at the time in how he chose to communicate that sentiment: whether he said it in a speech, say, or whispered it to a friend, or wrote it in his diary or published it in a book. That would never happen today, of course. We now believe that the “how” of a communicative act is of huge importance. We would say that Mao posted that power comes from the barrel of a gun on his Facebook page, or we would say that he blogged about gun barrels on Tumblr—and eventually, as the apostles of new media wrestled with the implications of his comments, the verb would come to completely overcome the noun, the part about the gun would be forgotten, and the the big takeaway would be: Whoa. Did you see what Mao just tweeted?