Sight is a different concept from Sound. Sound is related to Single. Single is related to Number. Number is related to Song. 
Happy is a different concept from Depression. Valley is a type of Depression. 
Sight <--DistinctFrom--> Sound <--RelatedTo--> Single <--RelatedTo--> Number <--RelatedTo--> Song 
Happy <--DistinctFrom--> Depression <--IsA-- Valley 