The quote from "The Last Unicorn" by Peter S. Beagle conveys a sense of profound disappointment and frustration from a father to his son. The father recognizes the son's vast potential but sees it overshadowed by his ineptitude and incompetence. It suggests that, despite the inherent abilities within the son, he is currently unable to harness them effectively. The father expresses the painful awareness that the son must embark on a personal journey to discover his true self and potential, which may take an eternity.

Additionally, the father's decision to grant his son eternal youth reflects a complicated blend of love and despair. He recognizes that the son will wander aimlessly, unable to grow or change until he figures out his path. This curse of eternal inefficiency is both a gift and a burden, showcasing the father's deep concern for his son's future. Ultimately, the quote encapsulates themes of inadequacy, the quest for identity, and the bittersweet nature of unconditional love intertwined with a feeling of hopelessness.