Charles Spurgeon Commentary Ecclesiastes 12:3

"in the day when the keepers of the house shall tremble, and the strong men shall bow themselves, and the grinders cease because they are few, and those that look out of the windows shall be darkened," — Ecclesiastes 12:3 (ASV)

And the strong men shall bow themselves,

These limbs, these legs of ours, begin to bend under the weight they have to support.

And the grinders cease because they are few,

The teeth are gone.

And those that look out of the windows be darkened,

The eyesight begins to fail.