Ecclesiastes 12:3 - Joseph Benson’s Commentary on the Old and New Testaments

When the keepers of the house The body, which is often and fitly compared to a house; whose keepers are the hands and arms, which are man's best instruments to defend his body from the assaults of men or beasts, and which, in a special manner, are subject to this trembling. And the strong men shall bow themselves Either the back, or the thighs and legs, in which the main strength of the body consists, and which, in old men, are very feeble. And the grinders The teeth, those especially which are commonly so called, because they grind the meat which we eat; cease To perform their office; because they are few Hebrew, כי מעשׂו, because they are diminished, either in strength, or in number, being only here one, and there another, and neither united together, nor one directly opposite to another, and consequently unfit for their work. And those that look out of the windows be darkened The eyes. By windows he understands, either the eye-lids, which, like windows, are either opened or shut: or, those humours and coats of the eyes, which are the chief instruments by which we see.