If you’re interested in software development—even if you’re a non-programmer who wonders if you might ever be able to learn this stuff, or if you’re interested in effective ways of teaching programming—you should watch this video of the Self system in action. (I recommend watching one of the big ones, even though they’re very large files, so you can see what’s going on on the screen.)
The Self project at Sun is, unfortunately, long dormant. The web page is still there, and if you’ve got a Mac and are still running Jaguar you can run it. There are still a few problems on Panther, unfortunately. (For that matter, if you have a Sparc machine running Solaris you can also try it out.)
But whether it’s directly useful today or not, it’s still fascinating history, and it’s sobering that although Self has influenced other technologies, those more successful systems are in many ways pale shadows of the original. It’s yet another vivid demonstration that much of the future of computing can be found in the past.