Professing themselves to be wise (paskonte einai sopoi). Sopoi is predicate nominative with einai in indirect discourse agreeing with paskonte (old verb, from phmi, to say, rare in N.T.) in case and number according to regular Greek idiom (Robertson, Grammar, p. 1038). Became vain (emataiwqhsan). Ingressive first aorist passive indicative of mataiow from mataio (empty). Empty reasonings as often today. Became fools (emwranqhsan). Ingressive first aorist passive of mwrainw, to be a fool, old word from mwro, a fool. An oxymoron or sharp saying, true and one that cuts to the bone. For the likeness of an image (en omoiwmati eikono). Both words, "a likeness which consists in an image or copy" (Lightfoot). See Philippians 2:7 for "likeness of men" and Colossians 1:15 for "image of God." Paul shows indignant contempt for these grotesque efforts to present pictures of a deity that had been lost (Denney). Why is it that heathen images of gods in the form of men and beasts are so horrible to look upon?