When I first discovered Smalltalk, it took me a while to get my head around the fact that in image based Smalltalk systems, source code is not written in flat files. Source code in files was so ingrained into my thinking, I had to unlearn and leave a lot of assumptions I have made. In most programming languages programs are written and defined using text files, typically source code is written in text files, using a text editor or an IDE such as Eclipse, IntelliJ or Visual Studio. At this point it just "dead code" in text files, there are no running objects, this is often referred to as compile time. Before a program runs, the runtime environment is created, the program’s source code is parsed, compiled and executed, and when the program finishes the runtime environment is destroyed, so in essence every time a change is made to source code the entire program is created from scratch. Smalltalk is pure object oriented and everything is an object and everything is achieved by sending messages to objects. In Smalltalk we dont use source code in text files to define programs (classes methods etc) instead objects are used to define Smalltalk programs, objects themselves are used to define new classes method etc. Now an object can exist only at runtime, and in Smalltalk everything happens on the fly, there is no such thing as compile time, Smalltalk is a runtime, it is not just a programming language, its a living system, it is a world of "living objects". This requires a paradigm shift and it often is one of the biggest barriers I find people face when entering into the Smalltalk world. Smalltalk pushes "Object thinking" to another level, but once you push past that barrier you enjoy all the benefits of working with living objects, you can interact with objects, inspect them modify, extended and change them on the fly. This is the main reason why Smalltalk environment have such powerful IDE's. read more ...