The year:
1984.
"Welcome to Macintosh."
A long wait as the disk grinds away...
Finally, the desktop appears. Command-E. My System disk, pops out. My Program disk, MacWrite, pops in. Grinding.
MacWrite pops out. Message: "Please insert disk: 'System 2.1'". System Disk pops in.
Doubleclick on the icon of the disk, MacWrite.
System disk pops out. Message: "Please insert disk: 'MacWrite'". MacWrite pops in. A little grinding.
MacWrite pops out. Message: "Please insert disk: 'System 2.1'". System Disk pops in.
Double-click on the MacWrite application icon.
System disk pops out. Message: "Please insert disk: 'MacWrite'". MacWrite pops in. A little grinding.
MacWrite pops out. Message: "Please insert disk: 'System 2.1'". System Disk pops in. A little grinding.
System disk pops out. Message: "Please insert disk: 'MacWrite'". MacWrite pops in. A little grinding.
I think you get the idea. This could repeat many more times.
Actually, this probably wouldn't happen with simply opening MacWrite, because it was small enough to fit a copy of the system on the same disk. But it could easily happen between the system + MacWrite disk, and the disk containing the file you were working with, especially if the file was large. And heaven help you if you were using a program that was more disk intensive than MacWrite, with a system disk, program disk, and data disk all flying around.