Jamieson, Fausset and Brown on Ecclesiastes 1:8

8. Maurer translates, "All words are wearied out," that is, are inadequate, as also, "man cannot express" all the things in the world which undergo this ceaseless, changeless cycle of vicissitudes: "The eye is not satisfied with seeing them," &c. But it is plainly a return to the idea (Ec 1:3) as to man's "labor," which is only wearisome and profitless; "no new" good can accrue from it (Ec 1:9); for as the sun, &c., so man's laborious works move in a changeless cycle. The eye and ear are two of the taskmasters for which man toils. But these are never "satisfied" (Ec 6:7; Pr 27:20). Nor can they be so hereafter, for there will be nothing "new." Not so the chief good, Jesus Christ (Joh 4:13, 14; Re 21:5).