Unit is related to Memory. Memory is related to Thought. Thought is related to Philosophy. Philosophy is related to Subject. 
Liberty is related to Abstract. Abstract is the opposite of Concrete. 
Unit <--RelatedTo--> Memory <--RelatedTo--> Thought <--RelatedTo--> Philosophy <--RelatedTo--> Subject 
Liberty <--RelatedTo--> Abstract <--Antonym--> Concrete 