Bonaventure — on Eccl 1:14 (Commentary on Ecclesiastes, Chapter 1)

“Here is touched upon the discovered vanity, because he profited nothing more, except that in his consideration he found vanity. And therefore he says: "I saw all things that are done under the sun," that is, I considered all things. "And behold, all is vanity," that is, vanity openly appears in them, because, as the Apostle says in Romans 8, "the creature was made subject to vanity, not willingly"; and not only vanity, but indeed also "affliction of spirit."”