The word humility signifies lowliness or submissiveness an it is derived from the Latin humilitas or, as St. Thomas says, from humus, i.e. the earth which is beneath us. As applied to persons and things it means that which is abject, ignoble, or of poor condition, as we ordinarily say, not worth much. Thus we say that a man is of humble birth or that a house is a humble dwelling. As restricted to persons, humility is understood also in the sense of afflictions or miseries, which may be inflicted by external agents, as when a man humiliates another by causing him pain or suffering. It is in this sense that others may bring about humiliations and subject us to them. Humility in a higher and ethical sense is that by which a man has a modest estimate of his own worth, and submits himself to others. According to this meaning no man can humiliate another, but only himself, and this he can do properly only when aided by Divine grace. We are treating here of humility in this sense, that is, of the virtue of humility.
The virtue of humility may be defined: "A quality by which a person considering his own defects has a lowly opinion of himself and willingly submits himself to God and to others for God's sake." St. Bernard defines it: "A virtue by which a man knowing himself as he truly is, abases himself." These definitions coincide with that given by St. Thomas: "The virtue of humility", he says, "Consists in keeping oneself within one's own bounds, not reaching out to things above one, but submitting to one's superior" (Summa Contra Gent., bk. IV, ch. lv, tr. Rickaby).
To guard against an erroneous idea of humility, it is necessary to explain the manner in which we ought to esteem our own gifts in reference to the gifts of others, if called upon to make a comparison. Humility does not require us to esteem the gifts and graces which God has granted us, in the supernatural order, less than similar gifts and graces which appear in others. No one should esteem less in himself than in others these gifts of God which are to be valued above all things according to the words of St. Paul: "That we may know the things that are given us from God." (1 Corinthians 2:12). Neither does humility require us in our own estimation to think less of the natural gifts we possess than of similar, or of inferior, gifts in our neighbours; otherwise, as St. Thomas teaches, it would behove everyone to consider himself a greater sinner or a greater fool than his neighbour; for the Apostle without any prejudice to humility was able to say: "We by nature are Jews, and not of the Gentiles sinners" (Galatians 2:15). A man, however, may generally esteem some good in his neighbour which he does not himself possess, or acknowledge some defect or evil in himself which he does not perceive in his neighbour, so that, whenever anyone subjects himself out of humility to an equal or to an inferior he does so because he takes that equal or inferior to be his superior in some respect. Thus we may interpret the humble expressions of the saints as true and sincere. Besides, their great love of God caused them to see the malice of their own faults and sins in a clearer light than that which is ordinarily given to persons who are not saints.
The four cardinal virtues are prudence, justice, fortitude, and temperance, and all other moral virtues are annexed to theses either as integral, potential, or subjective parts. Humility is annexed to the virtue of temperance as a potential part, because temperance includes all those virtues that refrain or express the inordinate movements of our desires or appetites. Humility is a repressing or moderating virtue opposed to pride and vainglory or that spirit within us which urges us to great things above our strength and ability, and therefore it is included in temperance just as meekness which represses anger is a part of the same virtue. From what we have here stated it follows that humility is not the first or the greatest of the virtues. The theological virtues have the first place, then the intellectual virtues, as these immediately direct the reason of man to good. Justice is placed in the order of the virtues before humility, and so should obedience be, for it is part of justice. Humility is, however, said to be the foundation of the spiritual edifice, but in a sense inferior to that in which faith is called its foundation. Humility is the first virtue inasmuch as it removes the obstacles to faith — per modum removens prohibens, as St. Thomas says. It removes pride and makes a man subject to and a fit recipient of grace according to the words of St. James: "God resisteth the proud, and giveth his grace to the humble" (James 4:6). Faith is the first and the positive fundamental virtue of all the infused virtues, because it is by it we can take the first step in the supernatural life and in our access to God: "For he that cometh to God, must believe that he is, and is a rewarder to them that seek him" Hebrews 11:6). Humility, inasmuch as it seems to keep the mind and heart submissive to reason and to God, has its own function in connection with faith and all the other virtues, and it may therefore be said to be a universal virtue.
CATHOLIC ENCYCLOPEDIA: Humility