Silk is related to Material. Material is related to Possession. Possession is a type of Relation. 
Biography is a type of Book. Cat is a type of Book. you are likely to find Cat in/at/on Trouble. 
Silk <--RelatedTo--> Material <--RelatedTo--> Possession --IsA--> Relation 
Biography --IsA--> Book <--IsA-- Cat --AtLocation--> Trouble 