Ecclesiastes 1:14 - Matthew Poole's English Annotations on the Holy Bible

I have seen, i.e. diligently observed, and in great measure understood. Behold; for it was a great surprise to me, and therefore may seem strange to you. All is vanity and vexation of spirit; and not only unsatisfying, but also troublesome, and an affliction or breaking to a man's spirit or mind. Or, as others, both ancient and modern translators, render it, a feeding upon wind, as these very words, save only that there is the verb from which this noun seems most probably deduced, are rendered, Hosea 12:1, where also it signifies a fruitless or lost labour, and a disappointment of their hopes and desires of satisfaction. And so this is a repetition of the same thing in other words, according to the manner of these books.