* The IDE/Debugger rocked. It was the killer app. You could explore/understand code in a way that I have yet to see rivaled in any other environment. I have use

* The IDE/Debugger rocked. It was the killer app. You could explore/understand code in a way that I have yet to see rivaled in any other environment. I have used PyCharm/XCode/Studio/VSCode/Emacs/Vim at regular levels. * BlockClosures. Reified and used ubiquitously. Did I mention reified? Since the language had no control flow builtins/keywords, it was all done in the library. And since Closures were fully first class objects that you could explore, understand, and extend, you could write control flow to your hearts content. * Simplicity. You didn't have to have a PHD in parsing to deal with the AST for Smalltalk. Building your own AST walker was a mid level exercise. I once saw a comparison between the Ruby AST and the Smalltalk AST. The Ruby one was like 10 times more complex to deal with all of the edge cases. I added a goto implementation for a lark in an afternoon. I wouldn't even know where to start to add goto to Python. An absurd example of course, but it highlights that you didn't feel like Dan Ingalls and the other inventors of Smalltalk controlled your destiny. They wanted you to go places with it.