In ancient Greece and Rome, they knew what we seem to have forgotten: your job as a leader is to persuade people to do great things in uncertain contexts, using only one tool: your words. Compelling leaders, as Aristotle might say, have three qualities that they express through three "languages":

Agility (or "Logos"). This language is about reading situations and getting things done. John is fluent in this language, but he needs to demonstrate that he is a learner. Words like this will work: "When we made this acquisition it seemed a good idea, but as I reflect on what has happened, three things are changing on us..."

Discover the other two languages of leadership inTony Golsby-Smith's blog for the Harvard Business Review.