Peter Merholz, founder of Adaptive Path (remember them? The budding UXer in me used to worship that company) and inventor of the word blog, dug up an old manual for the original 1984 Apple Macintosh.
It’s incredible how many basic things needed to be explained back then: graphical file systems, moving stuff around with a mouse, and (see pic above) the concept of scrolling.
These days, all we do is scroll scroll scroll. And we do it without even thinking about it.