In this case, the dwarfs are wise because, after working all day mining gems (mostly diamonds), they go off in search of their nearby (Canadian) post office. Or, in the case of Dopey, the bank. Once there, they convert their gems into War Savings Certificates which "keep your money fighting."
7 Wise Dwarfs
The Seven Dwarfs mine their diamonds for conversion into war bonds for the Canadian war effort.
