According to Martin Crowe, the celebrated former New Zealand captain, there are only three things certain in life: death, taxes and a hundred at the Adelaide Oval.
Another inevitability, of more recent vintage, is that you cannot keep Kevin Pietersen down for too long.
Mix the two adages together, and you get another Ashes batting monument for the renaissance man of England's line-up at the South Australia ground.
Four years after he made 158 on his first Test appearance at Adelaide, he has added a double century on familiar territory in the current Ashes encounter.
His method may have been similar, but the man himself is a slightly different animal. Back then he was brash, brilliant and self-assured. The unencumbered self-belief has been dented by experience, but at least he is brash and brilliant all over again.
Pietersen had 21 months and 39 first-class innings between centuries. The last time he made a ton he was still the England captain.
That fact did not escape those critics who said his batting mojo had gone when it was made clear to him he was not as important as he thought he was.
Pietersen always said it was only a matter of time before his best returned, and suggested a plane ticket to Australia would be just what was required.
He could not wait to get back there. Earlier this year, despite his lean spell, he said he was looking forward to the Ashes because it meant getting to play on great batting wickets.
The fact his best arrived in a torrent at the Adelaide Oval was inevitable.