Each concept has two definitions for each method provided in its reference class and object class.
Because Java-style OOP just doesn't have enough boilerplate. It sounds like the problems this solves have already been solved better by CLOS.
Can you help me out - what is the problem they are trying to solve in the first place?
The problem that different kinds of composition are not equally easy to specify. Some, non-blessed ones you have to put together with design patterns. He has an abstraction / implementation method that makes it all as easy as pie. At least that's what I took from it.