The game in 2adventure.rb will have two classes descending from Thing: the Treasure class and the Room class. The Treasure class adds a value attribute, which can be both read and written. Note that its initialize method calls its superclass in order to initialize the name and description attributes before initializing the new @value variable:

super( aName, aDescription )
@value = aValue

Here, if I had omitted the call to the superclass, the name and description attributes would never be initialized. This is because Treasure.initialize overrides Thing.initialize, so when a Treasure object is created, the code in Thing.initialize will not automatically be executed.

On the other hand, the Room class, which also descends from Thing, currently has no initialize method, so when a new Room object is created, Ruby goes scrambling back up the class hierarchy in search of one. The first initialize method it finds is in Thing, so a Room object’s name and description attributes are initialized there.