Re 2: I believe he had in mind a class used only to define some static methods. The original OO language, that is the lambda calculus, had no reference compari

Re 2: I believe he had in mind a class used only to define some static methods. The original OO language, that is the lambda calculus, had no reference comparison -- All You Can Do Is Send A Message is the slogan in general. http://www.erights.org/elib/equality/grant-matcher/history.html http://www.erights.org/elib/equality/grant-matcher/history.h... lists some less familiar ones. Given mutability, identity determines how a message to one object reference affects what happens when you invoke another one. If you go up from the above URL you'll see a bunch more discussion.