“Blessed are the meek, for they shall inherit the earth.” (Matthew 5:5) Meekness is an essential possession of the spiritual person. Jesus Himself was meek.
All things have been delivered to me by my Father; and no one knows the Son except the Father, and no one knows the Father except the Son, and any one to whom the Son chooses to reveal Him. Come to me, all who labor and are heavy laden, and I will give you rest. Take my yoke upon you and learn from me; for I am meek and lowly in heart, and you will find rest for your souls. For my yoke is easy and my burden is light. (Matthew 11:27-30)
The apostles of Christ taught meekness. Saint Paul mentions it in all his writings and Saint James insists upon it.
Who is wise and understanding among you? By his good life let him show his works in the meekness of wisdom. But if you have bitter jealousy and selfish ambition in your hearts, do not boast and be false to the truth. This wisdom is not such as it comes down from above from above, but is earthly, unspiritual, devilish. For where jealousy and selfish ambition exist, there will be disorder and every vile practice. But the wisdom from above is first pure, then peaceable, gentle, open to reason, full of mercy and good fruits… (James 3:13-17)
To be meek means to be gentle and kind, to be empty of all selfishness and earthly ambition. It means, in a word, never to return evil for evil, but always in everything to overcome evil by good. (Cf. Romans 12:14-21)
Meekness means to distrust and reject every thought and action of external coercion and violence, which in any case can never produce fruitful, genuine and lasting results.
Meekness is to have the firm and calm conviction that the good is more powerful than evil, and that the good ultimately is always victorious.
To refer once more to Saint John Climacus:
Meekness is an unchangeable state of mind which remains the same in honor and dishonor. Meekness is the rock overlooking the sea of irritability which breaks all the waves that dash against it, remaining itself unmoved. Meekness is the buttress of patience, the mother of love and the foundation of wisdom, for it is said, “The Lord will teach the meek His way.” (Psalm 24:9) It prepares the forgiveness of sins; it is boldness in prayer, an abode of the Holy Spirit. “But to whom shall I look,” says the Lord, “to him who is meek and quiet and trembles at my word.” (Isaiah 66:2) In meek hearts the Lord finds rest, but a turbulent soul is the seat of the devil. (The Ladder of Divine Ascent, Step 24)