This quote means that throughout history, effective and successful leaders have been aware of how important humor can be when dealing with people. Humor is a useful tool for leaders to reach their audiences and build relationships with people. With humor, a leader can help create a relaxed atmosphere, share ideas in a fun and lighthearted way, and make difficult topics more approachable. Humor also allows a leader to make the most of opportunities, diffuse conflict, and build trust and loyalty with their followers.