The Greek word for meek in Matthew 5:5 is praus. This word was was also used to describe an animal which has been domesticated, which has been trained to obey the word of a command, which has learned to answer to the reins. It is the word for an animal which has learned to accept control, such as the taming of a wild stallion. Thus, the meek man has self control. He has his passions and anger under control. He knows when it is the proper time to be angry at that which is wrong or unjust, and when not to be angry. Ruling your spirit is meekness. It takes great strength to have self-control and self-discipline. (Proverbs 16:32).
It was the lack of self control which ruined Alexander the Great, who, in a fit of uncontrolled temper in the middle of a drunken debauch, hurled a spear at his best friend and killed him. No man can lead others until he has mastered himself; no man can serve others until he has subjected himself; no man can be in control of others until he has learned to control himself.
--- Matoon