I thought about these principles after the English Wicketkeeper was hurt preparing for the test on Friday:
Wicketkeeper Prior then suffered a back spasm at 1000 BST shortly after the England players finished their football warm up and to make matters worse, England masseur Mark Saxby was struck on the head by a ball during Australia's catching practice.
Reflecting on his freak injury, Prior revealed it had been "really touch and go" over whether he would participate in the match.
"I had a bit of a shocker," he stated. "I've absolutely no idea how or why it happened, I was jogging along and suddenly had a back spasm. It was a tricky situation.
"The toss was pushed back 10 minutes and thanks to the Aussies for letting that happen. Ten minutes isn't a great deal to ask, but it was great they allowed it.
"The keeping was harder [than batting] but I should be fine. The good thing about a back spasm is that it can only get better. I will have a lot of massages this evening and carry on with the drugs this evening and I should be fine tomorrow morning."
Totally out of the blue......prior to a very very stressful situation.......