For who knoweth what is good for man in this life, all the days of his vain life which he spendeth as a shadow? for who can tell a man what shall be after him under the sun?
Who knoweth what is good? ... The ungodly know not what is really "good" during life, nor "what shall be after them," i:e., what will be the event of their undertakings; or what will be their state and their circumstances (Ecclesiastes 3:22; Ecclesiastes 8:7), not merely after their death, but an hour, a day, a year after the present. The godly might be tempted to 'contend with God' (Ecclesiastes 6:10) as to His dispensations; but they cannot fully know the wise purposes served by them now and hereafter. Their sufferings are more really good for them than cloudless prosperity: sinners are being allowed to fill up their measure of guilt. Retribution in part vindicates God's ways even now. The judgment shall make all clear. In Ecclesiastes 7:1-29 he states what is good, in answer to this verse. The only true good is "the true riches" (Luke 16:11).
All the days - Hebrew, 'the number of the days of the life of his vanity.' The fact that his days can be numbered implies their fewness. The shorter and the more shadowy (1 Chronicles 29:15) our life is, the more important it is that we should not hunt after shadowy vanities. Who can toil? If we could foresee that riches would always abide with us, we might have an excuse in making them our chief aim. But we know not how soon they and we shall part; therefore seek the true riches, and enjoy whatever present earthly good God gives.