Empty is related to Space. Space is related to Size. 
Flow is related to Rhythm. Rhythm is a synonym of Beat. Beat is a synonym of Crush. Crush is related to Romantic. 
Empty <--RelatedTo--> Space <--RelatedTo--> Size 
Flow <--RelatedTo--> Rhythm <--Synonym--> Beat <--Synonym--> Crush <--RelatedTo--> Romantic 