It seems that our nutritionist (wrong word?) is cooking Java in a serious manner.

Sorry, late-binding is an advanced topic in OOP. How important it is?
If you just know class inheritance and composition, you are object-BASED. once you understand late-binding, or lazy binding, or dynamic binding, you can be really counted as object-ORIENTED. Please pay attention to the difference between " based" and "oriented".

Sorry, you cannot find the dicussion about this topic in Core Java. Indeed, Core Java is a very good book about Java API. But no book is perfect and covers all things. I suggest you download Thinking in Java from www.bruceeckel.com and look into its dicussion about RTTI and Binding. You may have your servant read the book and have him explain the principle to you. In this way, you may restraint him from
wandering about this forum and talking about topless and table dance. -):

You are doing so great. Now I am afraid you may lay off Ji-Ang once you grab a programmer job.