this sore travail - namely, that of “searching out all things done under heaven.” Not human wisdom in general, which comes afterwards (Ecc 2:12, etc.), but laborious inquires into, and speculations about, the works of men; for example, political science. As man is doomed to get his bread, so his knowledge, by the sweat of his brow (Gen 3:19) [Gill].
exercised - that is, disciplined; literally, “that they may thereby chastise, or humble themselves.”