This expression implies that we can learn about a person’s true intentions by looking at what they do rather than what they say.
2. Apple of (one’s) eyea person or thing that is precious or loved above all else
Richard is so attached to his daughter that he would do anything for her. She’s the apple of his eye.
The boy won’t behave in school, but you can’t convince his parents. He’s the apple of their eye.
Centuries old, this expression stems from the ancient belief that the pupil of the eye was solid and shaped like an apple. The pupil was considered precious since one could not see without it.