The history of the music industry is inevitably also the story of the development of technology. From the player piano to the vinyl disc from reel-to-reel tape to the cassette from the CD to the digital download these formats and devices changed not only the way music was consumed but the very way artists created it.
Books constitute capital. A library book lasts as long as a house for hundreds of years. It is not then an article of mere consumption but fairly of capital and often in the case of professional men setting out in life it is their only capital.