The file icon is another digital GUI classic. It was also a part of the original icon set of the Xerox Alto.
The sample that is featured here is from Xerox Star. In the Xerox Star system the user would typically create new files by copying existing ones, which explains the "Blank Document" file title. The file icon follows the desktop metaphor to the letter and it has remained pretty much the same since 1973.
Xerox Alto 1973.