Christopher Paolini said this quote

“ They were quiet for a while, eating, then Oromis asked, Can you tell me, What is the most important mental tool a person can possess?It was a serious question, and Eragon considered it for a reasonable span before he ventured to say, Determination.Oromis tore the loaf in half with his long white fingers. I can understand why you arrived at that conclusion-determination has served you well in your adventures-but no. I meant the tool most necessary to choose the best course of action in any given situation. Determination is as common among men who are dull and foolish as it is among those who are brilliant intellects. So, no, determination cannot be what we're looking for. ”