I studied computer science near the end of 1980s, and wasn't taught OOP that formally.

With Pascal or C, when I understand the top-down design of functions, and the idea of black box, then everything just seem to make sense, as if there is a "oh I get it!" -- some kind of totally getting it and enlightenment feeling.

But with OOP, all I know was the mechanics: the class, instance, method, inheritance, polymorphism, encapsulation. It was like, I knew all the "this is how it is", but never had the feeling of "I totally get it", the enlightened feeling.

Would somebody be able to describe it, or point to a chapter in some book or paper which talks about OOP so that the reader can feel: "I totally get it!" on OOP?