Understand, ye brutish - These are the same expressions as in Psalm 92:6; (note), on which see the note.
Understand, ye brutish among the people - See Psalm 73:22. The meaning here is, “You who are like the brutes; you who see and understand no more of the character and plans of God than the wild beasts of the desert.” The meaning is, that they did not employ their reason in the case; they acted like beasts, regardless of the consequences of their conduct - as if God would treat people as he does the beasts; as if there were no retribution in the future world.
And ye fools, when will ye be wise? - How long is this stupidity to continue? When will you attend to the truth; when will you act as immortal beings; when will you suffer your rational nature to lead you up to just views of God? It is implied that this folly had been manifested for a long period, and that it was time they should arouse from this condition, and act like people. With what propriety may this language be addressed still to the great mass of mankind! What numbers of the human race are there now, who in respect to God, and to the purpose for which they were made, evince no more wisdom than the brutes that perish! Oh, if people were truly wise, what a beautiful world would this be; how noble and elevated would be our now degraded race!