Definitions: (1) showing skill or knowledge proving one as an expert of a subject; (2) having the ability or power to control <self or others>; authoritative

• A man who is a master of patience is master of everything else. — George Savile (1633 –1695) English statesman & writer
• You cannot control what happens to you, but you can control your attitude toward what happens to you, and in that, you will be mastering change rather than allowing it to master you. — Brian Tracy (1944-) Canadian-American motivational public speaker