What does the phrase “what is essential is invisible to the eye” mean in The Little Prince?

In The Little Prince, the phrase “what is essential is invisible to the eye” serves as the central moral of the fable. It is a secret shared with the prince by the fox, emphasizing that true understanding and value are found not through superficial observation, but through the heart and the establishment of emotional ties.1

The narrative contrasts this wisdom with the behavior of adults, whom the author portrays as narrow-minded and preoccupied with functions, possessions, or status. By suggesting that one must "see" with the heart, the story argues that the most meaningful aspects of life—such as love, friendship, and human connection—cannot be measured or perceived by the senses alone. Ultimately, the book serves as a reminder that the best things in life are simple and that real wealth is found in what we give to others.21