The apple of someone’s eye
This idiomatic phrase means a person or a thing that one cherishes the most. This idiom can be applied to inhuman objects, such as your favorite shoes or car, but it is more commonly used to refer to a favorite younger person or child. In Old English, the ‘apple’ was used in reference to the pupil of the eye. This is because, at that time, the pupil used to be regarded as a round spherical ball just like an apple. Since sight has been considered as the most important part of our senses, “the apple of someone’s eye,” which basically meant the center of the eye, became a metaphor for “the thing that is treasured the most.” A current example would be: “Mark is her only grandchildren and he is the apple of her eye.”
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