Change is a type of Thing. Variable is a type of Thing. 
Silver is related to Buddy. Buddy is related to Gold. Gold is related to Wealthy. Wealthy is derived from Wealth. 
Change --IsA--> Thing <--IsA-- Variable 
Silver <--RelatedTo--> Buddy <--RelatedTo--> Gold <--RelatedTo--> Wealthy --DerivedFrom--> Wealth 