What does Psalm 17:8 mean?

The language in this verse contains two images, both of which are significant; both are frequently used even outside of Scripture. These two phrases combine into a beautiful expression of God's caring love.

In Hebrew, the word i'son most simply refers to "blackness" or "darkness." The phrase i'son bat ā'yin literally means "the blackness of the eye." This means the pupil: the dark circle at the center of the human eyeball. This is arguably the most closely protected part of the body: something we take great pains to protect and which we never allow to be struck or scratched. David's plea, then, is for God to protect him with that level of care and tenderness. At some point, the term "apple of the eye" became the English idiom referring to the pupil, and so many translations use that phrase when referring to this idea.

Other scholars suggest the Hebrew word 'iysh, meaning "man," can be rendered as a diminutive, "tiny man," using the word i'son. In a context of protection, this refers to the fact that one can sometimes see themselves reflected in the pupil of the other's eye. Interestingly, the English term "pupil" developed from terms related to orphans, which was then applied to "students." At almost the same time, words related to precious things like children and infants, reflected in the eyes, inspired the use of the word "pupil" for the dark center of the eyeball.

The second image, "the shadow of your wings," evokes a mother bird pulling her young close to protect them (Matthew 23:37). Deuteronomy 32:11 employs this image to recall God's gracious care of Israel. Chickens, among the earliest domesticated birds, are famous for tucking their children under their wings for warmth and safety. Other birds cover their young to shield them from sun, rain, or the eyes of predators (Psalm 17:9). So, too, does David want God to hold him close and keep him safe.