Joy takes a toll, and Marcelo Bielsa was asked afterwards about heart attacks. "When you change the destiny of the game in the last seconds, you have to take into account (that) hazard." Quite.
Only football can do this. Humans have done a lot of damage to this planet over millennia. But over the last 150 years some humans have kicked a football into a net at just the right moment and made it all feel like a price worth paying.
Bielsa doesn't bring happiness. Bielsa brings principles and duty, and faith that the effort of adhering to them will result in happiness in the end, and the understanding that it probably won't.
Winning promotion to the Premier League with Leeds United is Pontus Jansson's dream. This season dreams might come true, and Jansson is recognising, after the World Cup made him a latecomer to Marcelo Bielsa's revolution, that the more serious he is, the more true that dream could be.
While Reach's speculative strike had the satisfying audacity of a stunt, Klich made something artful, deliberate and beautiful. It's the difference between watching two magpies have a fight in your garden, or watching a nature documentary narrated by David Attenborough.
The lingering impression from seeing Bielsa take on Pulis was not that one style of football works better than another; neither is going to suddenly change their minds now, anyway.
Saiz dribbled towards the centre, swerving through two tackles, and was fouled by the third; he sprang to his feet, offered his hand and pulled the player who had fouled him back to his feet, desperate to play. We were 2-0 down in stoppage time in the Carabao Cup here.
Kalvin Phillips threw himself at the ball to stop Norwich taking a shot at Peacock-Farrell, and it was a moment when Bielsa's principles of complete commitment from first to last combined beautifully with Leeds United's principles of side before self and effort for the cause.
Bielsa sits, crouches or prowls, eyes on the action, with one aim in mind that inspires countless thoughts and strategies: get this plan working. Bielsa has one way to play. His flexibility comes from the extraordinary lengths he'll stretch to so that he doesn't have to change a thing.
At times you could feel the strain Leeds' players were under; it would have been easy to revert to last season's type, to concede a stupid goal, have a couple of players sent off, give it loads of bollocks in the second half when it was too late then end up losing amid boos. But that was then.