Java: Rationale of the Object class not being declared abstract

Question

Why wasn\'t the java.lang.Object class declared to be abstract ?

Surely for an Object to be useful it needs added state or behaviour, an Object class is

Answer 1

I am not sure this is the reason, but it allows (or allowed, as there are now better ways of doing it) for an Object to be used as a lock:

Object lock = new Object();

....


synchronized(lock)
{
}