Smalltalk-72 Instruction Manual

I don't remember how, but I end up reading some parts of this relic.

Some notes:

Objects

Every entity in Smalltalk's world is called an object. Objects can remember things and communicate with each other by sending and receiving messages. Every object belongs to a class (which is also an object). The class handles all communication (receiving a message and possibly producing a reply) for every object which belongs to it.

Message Sending and Receiving

A message is sent to an object by first mentioning the object and then mentioning the message.

The Notion of Class

The basic class definition deals with just two ideas:

1. The notion of creating objects which have independent existence and memory.

2. The control of the flow of evaluation by sending and receiving messages in various ways.

Almost fourty years... that's a lot of time.. Here is the link:
http://bitsavers.informatik.uni-stuttgart.de/pdf/xerox/parc/techReports/Smalltalk-72_Instruction_Manual_Mar76.pdf

PS: Starting at page 117 there is a description of how to implement simulations, that seems to be pretty interesting.