You can't fight City Hall. That American expression that has its origin somewhere in that colourful country's disaffected past.
It was coined by those who were put upon, cheated, hookwinked or done down by bureaucracy. Its message is simple. You can't expect to take on an entrenched establishment and win.
Having been dumped out of the championship in June by Louth, Kildare pulled themselves up by their bootstraps and battled through the qualifiers to an All-Ireland semi-final.
They did so against the odds. In early summer rumours reached me that manager Kieran McGeeney's position was under threat. But McGeeney wasn't for turning. He got the Lilies shipshape and sailed on. He and his players had one focus. To win.
Yesterday they came up against a brick wall. The brick wall of City Hall.
What was obvious to TV viewers and many spectators in Croke Park was missed by referee Pat McEnaney and his umpires.
In the 12th minute, Down scored a goal. There was only one problem. It wasn't really a goal. It was a square ball. But the decision rattled Kildare's backs and Down added on a couple of points when the going was good.
When the final whistle blew, Down progressed to the All-Ireland final by a winning margin of just two points.
And the public witnessed another day of GAA logic.
Kildare had been immense. They left the field with heads bowed but yesterday they weren't losers. It was simply a case that they didn't win. Kildare became just the latest team to come out on the wrong side, the downside, of the GAA's unique City Hall logic.
Down were jubilant. Kildare sank to their knees. It had been an epic battle.
The Leinster team had never allowed their Ulster rivals get away from them. Even at the death, a Kildare shot rattled the crossbar. The width of one of the hairs that stood up on the back of 62,182 necks in Croke Park as Robert Kelly let rip, is all that denied Kildare a first All-Ireland final appearance since 1998.
The teams had been level at half-time. In the second-half, Down had lived dangerously, going for impossible goal shots when they could have nicked a point to pile pressure on Kildare. They'd almost handed the game back to Kildare. Almost.
Kildare not only hit the crossbar. They hit the upright. They hit the post. They had what looked like a perfectly valid point waved wide by the umpire. And still they kept coming. The matter of the questionable Down goal had gone off the radar by the time McEnaney advised Robert Kelly that time had run out and that his final free kick would have to count.
And this is what it came down to. This is what months of hard slog, arduous training, punishing fitness programmes, do-or-die knock-out match after match six weeks in-a-row had come down to. One kick. One crossbar. One whistle.
And then a generation of people's hopes, dreams and prayers crumbled like sandcastles at full tide. The pain was off the scale. Sporting despair might not be a term in the medical textbooks. But it's nonetheless real.
Within minutes of McEnaney's ultimate toot, both sets of players had gathered in huddles in the centre of Croke Park. The body language from the red and black group sang a song of hope, expectation and more than a little relief.
At the centre of the Kildare group, Kieran McGeeney stood resolute. He'd shaken hands. He'd patted players on the back. Now he stood surrounded by wounded warriors.
What the four X could he be saying to them, these players who'd played 'til the death?
I asked him afterwards. In public. Despite the weight on his shoulders and the crushing disappointment, Kieran engaged with the question. He didn't come out with any soft soap PR waffle. That's not his style. In defeat McGeeney bit the bullet, looked me in the eye and brought the whole Championship endeavour right down to basics. The question was, "What could you tell them?"
"You just tell them you're proud of them," said Kieran. "That's what sport's all about. You can go through the world championship in golf, or snooker or whatever sport and you're going to lose games. You're going to lose big games. It's hard, you know."
There's more. He's thought of something. "Sometimes I wonder... maybe that's why the relationship between players and press is so prickly. People find it hard to realise, that when you walk out there you put yourself up to be graded as a man. You grade those men. Their personalities, their livelihoods from one to 10 and that's how other people read them and judge them. They're willing to do that. That's what you do as a sportsman. It's tough. You throw everything into it. You don't look at defeat as an option and when it comes you haven't prepared for it. To put your heart and soul into something like that (match) there and see it ripped away from you, it's tough."
Anyone who knows anything about Gaelic football knows why the Kildare players would pay attention to what McGeeney has to say. I don't stop him. He's in full flight.
"I know what it feels like," he reminds me. "I've been there, done that. I try to tell them that the hurt can help. It can push them on. It can bring them to bigger heights. It's part and parcel of sport. It's part and parcel of life. It's how you deal with it. Of course they're going to be disappointed but they can't go home and feel sorry for themselves. They're good players. They're good athletes. They're good lads. And they have to remember that. That isn't a measure of who you are. Just because it tipped one way in the last couple of minutes. I just told them to remember that and be proud of themselves."
This Kildare side will be knocking on a few doors next season. No mistake. They've made progress this year.
McGeeney calls this year's adventure "a learning curve".
Looking back at the defeat by Louth, he says, "I don't think we got a hammering. We put up 19 points that day. We were probably a wee bit loose in defence. It gave us a chance to tweak. The whole year was in and out, trying to get a settled team. I think we stepped up another gear this year again. I definitely believe that. It's a step forward and it's a very young team. They definitely can do something. It's hard work. But hopefully they've learned a lot from this year.
"That's what you have to do," said the manager resolutely. "It's a learning curve for everybody."