Material is related to Substantial. Substantial is similar to Essential. 
Purpose is related to Mission. Mission is a synonym of Commission. Commission is a type of Equip. Equip is a type of Enable. 
Material <--RelatedTo--> Substantial <--SimilarTo--> Essential 
Purpose <--RelatedTo--> Mission <--Synonym--> Commission --IsA--> Equip --IsA--> Enable 