The Apple of My Eye

One of the oldest phrases in this whole repository. It first appears in Old English in a work attributed to King Alfred the Great, from around 885 AD, and shows up repeatedly in the Bible, including Deuteronomy 32:10 in the King James Version. Originally, "apple" here meant something more literal: the word for apple and the word for a round, solid object (like a pupil) were closely related in Anglo-Saxon, so the "apple" of the eye was simply the pupil itself, the small, precious, easily-damaged core of your vision. Something or someone described as the apple of your eye was, quite literally, as important to protect as your own sight.