...Nygaard and Dahl invent Simula in the mid '60s. Kay stumbles upon Simula while working at Univ. of Utah and has light bulb go off - invents Smalltalk. A decade later, Bjarne Stroustrap writes C with Classes which borrows heavily from Simula but ignores the advances of Smalltalk. Bottom line is that every OO language has borrowed from the Simula language.

The biggest problems with Simula were related to static typing and inheritance. Simula only supported single inheritance. For the simulations that it was designed for at the time, that was sufficient. There have been some improvements in static OO languages since that time but not that much. In turn, most of the modern OO languages ignored some cool features of Simula such as coroutines.

Of course, if you ask Todd, He'll probably inform you that Smalltalk is probably the only OO language that actually went about improving upon Simula. :-)

Nygaard later worked on the BETA programming language but it never really caught on. The compiler and associated libraries had to be purchased and it was anything but an open project. And the syntax is a bit strange - borrowing a lot from Lisp.

Anyhow, Nygaard is well respected for his accomplishments. That said, I can't say that the paper you pointed to is very enlightening. Better to go play with [link|http://onestepback.org/articles/poly/simula.html|Simula] or [link|http://onestepback.org/articles/poly/beta.html|Beta], if you want to see his less nebulous accomplishments.