Fondly remembered:

In 1971 I was working for a timeshare company that enabled people all over the country to write and run computer programs on our centralized systems. We had a satellite office in Washington DC. I programmed a communications computer that simultaneously served sixteen Washington-area users, saving a lot of AT&T communications costs.

The Washington people asked if we could add a printer to their site, for efficient remote printing. My manager, Larry, put me on this project, and I gave what turned out to be a fairly reasonable calendar estimate for the job. It was a lot of work. I had to create many different modules and communication paths, because our system, at that time, had no notion of a remotely connected printer.

In the middle of the project, as planned, I, my wife and our sixteen month-old daughter took a twenty-nine day vacation to ramble around Europe. It was the longest vacation I've ever taken from work, and it was a grand pleasure.

About ten days before we left, Larry asked me how well-documented my project was. I told him I was very much in the middle of things, and there wasn’t any documentation of the planned software at all.
“I want you to document it,” Larry said. “While you're away, I may have someone else work on the project.”

That was fine with me. I was excited to think that I might return from Europe to find that the project was making progress. But I wanted to get the software into a certain state before I left. Doing the documentation in addition took a lot of time, and I just about killed myself getting ready to leave.

I handed everything over to my boss, and came back, well-rested, twenty-nine days later. “Larry,” I asked, “has anyone been working on my project?”

“Oh ... uh, no. No,” he said, “it’s right where you left it.”

I can’t tell you how furious I was. I had done all that extra work, and for what? But Larry was one of the nicest managers I ever had, so I didn’t let my anger show. I unpacked my project. Now ... where was I?

Twenty-nine days is a long time.

As I read through my documentation, the work came back to me, in all its detail. What I had already written; what to do next; what every piece of code was for; and exactly what was missing. And of course, I realized why Larry had made me write that documentation.