Smalltalk [L1 ] is a pure object environment and programming language. Read the link to learn more.
Smalltalk is the oldest mature pure object-oriented language. It is brilliant, simple, and has only a few keywords. It is similar to Tcl in that the control structures are not part of language.
Almost all good things known in new hype-languages come from Smalltalk. That is
Also many popular program-techniques were developed under Smalltalk first. That is Extreme Programming (with Unit-tests), Refactoring Tools, Visual Programing, MVC (Model View Controler).
Smalltalk has also good designed standard libraries (Collections, Process Controll, IO).
Squeak [L2 ] is a popular Smalltalk implementation with an active community, and several interesting features. If you want to play with Smalltalk, Squeak is a good start. - TP, whose first OO language was Smalltalk.
Why is not Smalltalk the first most popular object-oriented program language? The reasons could be:
XOTcl is an object-oriented extension for Tcl that has some characteristics from Smalltalk. It is also dynamic and has metaclasses and also have the same feeling. XOTclIDE provide Smalltalk like IDE (Squeak, Version Control as in Envy)