Yes, that's the real point of Smalltalk.

I'm incredibly frustrated by environments like Ruby on Rails which pay lip service to the idea of "everything is an object" — but those objects are just a cesspool of hollow non-evolving throwaways that get built up and torn down on every request.

It's the difference between a castle made out of toy blocks and the Buckingham Palace.

The liveness of the environment is really stellar. Other languages have REPLs, but once you've entered your code, it gets compiled and saved in some internal format. In most languages I've tried, there's been no way to retrieve the originally written code. That's possible with Smalltalk.

That was a real eye-opener for me. In most languages (Java, C#, ...) the standard library is like a mountain range - you can climb it, but you cannot change or move it. In Smalltalk, it is like a living room, where I change or move the furniture around as I please.