Ye yourselves have seen it - Your own experience and observation have shown you that the righteous are frequently in affliction, and the wicked in affluence.
Why then are ye thus altogether vain? - The original is very emphatical: תהבלו הבל hebel tehbalu, and well expressed by Mr. Good: "Why then should ye thus babble babblings!" It our language would allow it, we might say vanitize vanity.
Behold, all ye yourselves have seen it - You have had an opportunity of tracing the proofs of the wisdom of God in his works.
Why then are ye thus altogether vain - Why is it that you maintain such opinions - that you evince no more knowledge of his government and plans - that you argue so inconclusively about him and his administration! Why, since you have had an opportunity of observing the course of events, do you maintain that suffering is necessarily a proof of guilt, and that God deals with all people, in this life, according to their character? A close observation of the course of events would have taught you otherwise. Job proceeds to state what he supposes to be the exact truth on the subject, and particularly aims, in the following chapter, to show that the ways of God are inscrutable, and that we cannot be expected to comprehend them, and are not competent to pronounce upon them.