Claude C. Hopkins was perhaps an unlikely figure to revolutionize the business of harvesting and using human attention, but that is what he did in the early twentieth century, when he became one of advertising’s greatest innovators. Still in its infancy, this new form of communication was, as we have said, the means by which attention could be converted into cash, for Hopkins was a particular master of the art of using attention to create demand for new products.

Tim Wu, The Attention Merchants, loc. 76