" Every few hundred years, throughout Western history, a sharp transformation has occurred. ... Our age is such a period of transition." From memory, Drucker suggested that the current transition can be dated from around 1950 ..."
Oh, humph. You want a sharp transformation, look at the period from 1840 to 1860. In 1840, if you wanted to send a message or a package to someone else, you gave it to a guy on a horse or in a sailboat who would proceed at a walking pace in the direction of the recipient. Getting news or goods between New York and San Francisco or London took weeks and was subject to large unpredictable delays.
By 1860, there were telegraphs, railroads, and steamships, so messages could go anywhere in the developed world in a few minutes, and goods were delivered on predictable schedules. These were at least as wrenching changes as anything in this century, and we're still getting used to them.