Prove all things (panta [de] dokimazete). Probably de (but) is genuine. Even the gift of prophecy has to be tested ( 1 Corinthians 12:10 ; 1 Corinthians 14:29 ) to avoid error. Paul shows fine balance here. Hold fast that which is good (to kalon katecete). Keep on holding down the beautiful (noble, morally beautiful). Present imperative kat-ecw (perfective use of kata- here).