The phrase describes something cherished above all else. Often used to denote a person who is deeply loved and treasured, it also extends to objects or endeavors held in exceptionally high regard. For example, an author might consider their most recent novel their “apple of my eye”, representing the work they are most proud of. The inclusion of “book” indicates the focus is specifically on literary works that hold this special significance.
The expression’s significance lies in highlighting the intense affection or value placed upon the subject. This can reflect the culmination of dedication, passion, or personal investment. Historically, the idiom has roots in biblical texts and ancient literature, evolving to represent the protection and care one affords to something deeply prized. Such literary creations are frequently imbued with personal meaning and reflect the creator’s unique perspective.