Humility is not thinking less of yourself, it is thinking of yourself less.C.S. Lewis — Mere Christianity, 1952
Humility is the accurate assessment of one's own nature, capacities, and limitations — neither inflated by vanity nor deflated by false modesty. It is not self-deprecation. It is the honest recognition that you are one person among many, that your perspective is partial, that much of what you know you did not discover, and that the conditions which made your achievements possible were not entirely your own creation.
Confucius required it of the superior person: the junzi who claims to know what he does not know is not displaying confidence — he is demonstrating that he cannot be trusted. The willingness to say I do not know is not weakness. It is the foundation of genuine learning, because the person who already knows cannot receive what is new.
Napoleon Hill listed it implicitly in his account of the mastermind alliance: the person who cannot listen to others, cannot acknowledge that their perspective is partial, cannot give credit to those who contributed to their success, will eventually find themselves working alone. And working alone, in Hill's framework, is the single most reliable predictor of limited achievement. The capacity to form genuine alliances — to recognize what others bring that you do not have — depends entirely on the humility to know your own limits.
The philosophical danger of humility is the imitation of it. False humility — the performance of self-deprecation designed to elicit reassurance or to avoid the vulnerability of genuine confidence — is not a virtue. It is a form of manipulation. Genuine humility is quiet. It does not announce itself. It is visible in the person who takes credit accurately, attributes assistance genuinely, and continues to learn because they have not mistaken their current knowledge for the limit of what is knowable.