English up can be used to express completion or thoroughness: eat it up 'eat all of it', beat him up 'beat him thoroughly'. What research exists on this construction, from any angle (syntax, historical semantics, Construction Grammar, etc.)? How did it arise and when? What are its exact semantics? How is it that up can function as an argument for verbal valency purposes ('He swept the dirt up' but *'He swept the dirt') given that it appears to lack any of the usual semantics of arguments?