But wilt thou know? (qelei de gnwnai?). "But dost thou wish to know?" Ingressive aorist active infinitive of ginoskw (come to know). James here introduces a new argument like Romans 13:3 . O vain man (w anqrwpe kene). Goes on with the singular objector and demolishes him. For "empty" (deficient) Paul uses aprwn (fool) in 1 Corinthians 15:36 and just anqrwpe in Romans 2:1 ; Romans 9:20 . Barren (arge). See 2 Peter 1:8 (not idle nor unfruitful) and Matthew 12:36 , but Hort urges "inactive" as the idea here, like money with no interest and land with no crops.