"The very essence of leadership is that you have a vision. It's got to be a vision you articulate clearly and forcefully on every occasion. You can'

"The very essence of leadership is that you
have a vision. It's got to be a vision you articulate clearly and forcefully on every
occasion. You can't blow and uncertain trumpet."

This quote contains two statements that I wholeheartedly agree on and one which I am not too sure about. "The very essence of leadership is that you have a vision" - There are countless factors that go into leadership, but one of the few that leadership cannot be without is vision. Without a vision, a leader can just be assumed to be a motivational speaker or a charismatic boss. A vision is needed for change, which is the primary goal of a leader, to lead his subordinates.
"It's got to be a vision you articulate clearly and forcefully on every occasion" - I do not believe that you need to either forcefully articulate your vision, or do it on every occasion. This sounds more like you are making your vision into a vocabulary test for second grade students to pass.
"You can't blow an uncertain trumpet" - This speaks volume to me. As a leader, you MUST brainstorm and plan out (blueprint, if you will) your vision to the full extent of what it can be. When you do start to articulate your vision, you know the ins and outs of your vision to establish confidence in it so your subordinates do not take you and your vision for granted.