As per Alan Kay on the Squeak mail list in 1998:
…Smalltalk is not only NOT its syntax or the class library, it is not even about classes. I’m sorry that I long ago coined the term “objects” for this topic because it gets many people to focus on the lesser idea.
The big idea is “messaging” — that is what the kernal of Smalltalk/Squeak is all about… The key in making great and growable systems is much more to design how its modules communicate rather than what their internal properties and behaviors should be. Think of the internet — to live, it (a) has to allow many different kinds of ideas and realizations that are beyond any single standard and (b) to allow varying degrees of safe interoperability between these ideas.
If you focus on just messaging — and realize that a good metasystem can late bind the various 2nd level architectures used in objects — then much of the language-, UI-, and OS based discussions on this thread are really quite moot.