There is hardly a more common error than that of taking the man who has but one talent for a genius.

A single conspicuous ability is easy to mistake for general excellence, and the mistake gets made about others and about yourself. Someone speaks well, or has a quick memory, or does one narrow thing brilliantly, and the impression spreads across every capacity they have never demonstrated. Then the responsibilities arrive that need the other capacities, and the gap becomes visible all at once.

Before relying on someone, ask what you have actually seen them do rather than what you assume follows from it. Apply the same to yourself: name the thing you are genuinely good at, then name the adjacent things you have merely been credited with.