The Alan Kay viewpoint (he is NOT the inventor of OOP [1]) is considered the least helpful viewpoint on OO design. The “magical” and unhelpful “its all about messages” perspective, that helps you not at all unless one is talking about the internal implementation of a platform like Smalltalk. Consider the views of the real inventors - Nygaard and Dahl.

[1] I don't think I invented "Object-oriented" but more or less "noticed" what was really powerful about just making everything from complete computers communicating with non-command messages. This was all chronicled in the HOPL II chapter I wrote "The Early History of Smalltalk". — Alan Kay