"apple of one's eye" 这一词最早出现於圣经里：诗篇17:8：Keep me as the 'apple of the eye' ,hide me under the shadow of thy wings;《申命记》三十三章的第十节：In a desert land he found him,in a barren and howling waste.He shielded him and cared for him; he guarded him as the 'apple of his eye'.
跟东方一样,在西方,人们也一直都把苹果视为一种吉祥的水果.不是还有另一句英文谚语："An apple a day,keeps doctor away".所以"apple of one's eye"就是指「珍贵的东西」,也就常被引申为「珍爱的人或物」.
所以说You are the apple of my eye,意思就是指说：你是我的挚爱,或是同等意思.