The sudden turnaround in England's fortunes in the Ashes was stunning. One minute, they were floating along on top of the world... and then within an hour the entire logic of the series had been turned upside down as Mitchell Johnson tore through their middle order.
Now the whole series is up in the air.
The moral? Well, don't ever get too confident when you're on top.
But the whole affair set me in mind of two things. The first is the role of momentum, in sport as in life. Johnson had cracked a quickfire 62 as a batsman the night before. That seemed to puff him up and give him the confidence to go on with the ball. When you get on a roll, the seratonin and the adrenaline flow, and you bear all before you. Silly England for bowling around his ears and getting his blood up. A more controlled approach might have chilled his blood still further after his lamentable display in the First Test. The whole affair reminded me of Graham Swann and Stuart Broad's rearguard action at Headingley in 2009, when their defiance seemed to lift the team in the final Test at The Oval (which England won).
Quite a lot of the banter or 'sledging' might also make my second point. Jimmy Anderson had a word with Johnson on Thursday night; then on Friday quite a lot of words were exchanged, and not only among the players. Steve Finn made what we might call an 'assertive' gesture towards the crowd as well. But as a historian, I think we should see all this for the storm in a teacup that it is. Want aggression? What about the 'bodyline' tour of 1932-33, where the English narrowly avoided being lynched during the Third Test at Adelaide as they persisted in bowling unsportingly 'at the man'.
Conduct has usually got better since then. Age of the gentleman? Don't you believe it.