Ecclesiastes 1:15

That which is crooked cannot be made straight: and that which is wanting cannot be numbered.

Cross-references

In Ecclesiastes 3:14, God's eternal work contrasts with the crookedness humans cannot fix—only God's actions endure.

In Ecclesiastes 7:13, the same 'crooked' and 'straight' imagery reinforces that only God can make straight what He has made crooked — a direct echo of the futility theme.

Isaiah 40:4 Contrast

In Isaiah 40:4, God promises to make the crooked straight — a direct contrast to Ecclesiastes' claim that it cannot be done by human effort.

In Isaiah 42:16, God promises to make rough places level — contrasting with Ecclesiastes' claim that crooked cannot be straightened by humans.