Someone once described the opening of a talk to me as a take-off, and I have thought of it that way ever since. If a plane took off and it was really scary, you would spend the whole flight wondering whether the pilot could fly it. The take-off and the landing are where the pilot works hardest. In the middle there is a kind of autopilot, and a good speaker gets there too, flowing from one idea to the next.

I watched a clip of Derren Brown tonight making the same point. He described the moment at a magic show when the next act walks out. Before they have even reached the microphone, “you’re either totally on their side and going, ‘Wow.’” Or you aren’t. What decides it, he thinks, is whether the person is at home on stage, and if they are, “we in the audience feel relaxed in their company.”

Psychologists have tested this. In one study, strangers watched a teacher for just two seconds, with the sound off, and rated them. Their snap judgements closely matched the ratings the teacher’s own students gave after a whole term of lessons.

So I always script the first couple of minutes of a talk, about 240 words. Knowing exactly how I will start lets me relax, and when I relax, so does the audience.