If it ain't working, do something different. Arsene Wenger might not want to believe in that wisdom but Antonio Conte is strolling towards a Premier League title because of his brilliance at managing change.
Defeated by three goals when these sides met in late September, Chelsea deserved revenge by at least the same margin here. Rarely has good coaching so reconfigured a team mid-season. Who needs transfers? And, as Conte explained in the press room after the match, the difference goes far deeper than tactics and formation.
That loss at the Emirates followed defeat by Liverpool and, five months ago, Conte did more than switch to 3-4-3 and impose a more counter-attacking game. He worked on finally clearing the minds of players still hung over from a discordant previous season. He challenged them: Who are you, he asked.
"I changed a lot. After the defeats against Liverpool and Arsenal, I said we faced great teams and we were not a team. We were 11 players playing," said Conte. "And I remember also my words. I said, 'You must show on the pitch you are a good team, you are not a good team just because you are at Chelsea.'
"After, the situation totally changed. The will to fight together, to fight as a team, to try something important this season... Now we are different if you compare us to the first game against Arsenal."
Conte has won 61 of his last 73 domestic league games and looks the full package: motivator, tactician and master of those tiny details that the best coaches finesse to win games.
Twelve months ago, England belatedly appreciated Claudio Ranieri's talents. Now a cloistered football country has finally woken up to another Italian. Conte was very much the footnote when, at the start of the campaign, people talked about all the great managers in the Premier League but now he stands atop it, clear and stretching the distance between himself and the more vaunted Wenger, Pep Guardiola, Jose Mourinho and Jurgen Klopp.
Conte has won 61 of his last 73 domestic league games and looks the full package: motivator, tactician and master of those tiny details that the best coaches finesse to win games. He erupted in cataracts of Italian invective just before half-time, haranguing his staff, and his sheepish explanation gave an insight into his passion for thoroughness.
Why the explosion? It was over minutiae.
"Angelo Alessio (the assistant first-team coach) is a victim, he's always a victim," said Conte with a rueful smile. There had been a series of corners to Arsenal.
"I wanted to change some positions in the second corner. Arsenal put six men (in the area) and we lost a man at the edge of the box. I tried to shout to my players and I told my assistant to try and send that message."
The message did not get through, so poor Alessio, Conte's sidekick since they were coaching at Siena seven years ago, got coated.
"Angelo, he knows very well my passion," the manager said.
Among his Chelsea feats is rendering John Terry's marginalisation a non-issue. To a question about Gary Cahill's growing maturity and captaincy, Conte skilfully turned the agenda towards his club skipper, taking the opportunity to massage egos and pay respects.
"It is important to underline our captain is John Terry. He's being the captain very well. He's helping not just me but his team-mates. His attitude is fantastic," Conte said.
This week a year ago, Ranieri made his decisive move, Leicester beating Liverpool and Manchester City in consecutive games to take charge of the title race. Chelsea's four points from games with Liverpool and Arsenal seem similarly significant. Ranieri was masterful, both through motivation and tweaks of tactics, in maintaining that advantage. Conte's record of three titles in three seasons with Juventus suggests he will prove equally adept at seeing the Blues home.
The psychological work on his squad started immediately.
"I don't slip," he said. "I don't want my players to slip. I have players with a lot of experience because they won a lot in their careers. They know that right now they haven't won the title. It's important to know this and keep our antenna very high."
THE TIMES, LONDON