Belief is a funny concept.

There’s no real way to measure it. You won’t find a way to truly quantify it in match statistics, you won’t physically be able to see it when someone’s playing a pass and you can’t unequivocally tell if an individual genuinely possesses it to their core when the pressure is on.

Yet belief is what Ange Postecoglou has been asking for since arriving in Glasgow.

At his fan media press conference, he said his football philosophy was based on creating “special things” and added that “the challenge we’re going to face, firstly, is just getting our guys to believe in that – it’s not an easy way to play football because you’ve got to be really brave”.

Since then the notion of belief has been brought up relatively often as the Australian seeks to instil his principles at Parkhead – so far with mixed results on the pitch.

“What we’re trying to do will happen a lot quicker if people believe in me as a person,” Postecoglou said before the 6-2 pre-season defeat against West Ham. Afterwards, he returned to the topic by saying: "That’s when your belief gets tested... part of the process is to stand up to things like this, when it hasn’t gone well.”

Then, as the crucial Champions League qualifying second leg against FC Midtjylland approached, he insisted: “What’s important for us is that we maintain our line and our football and our belief in what we’re going to do.”

There’s a theme developing here. You get the picture.

Even before Saturday night’s 2-1 Premiership defeat to Hearts, Postecoglou was there on the Tynecastle touchline saying his players had to “stick to the principles we’ve been working on and play the kind of football we like”.

READ MORE: Detailed Celtic player ratings as Carl Starfelt makes difficult debut in disappointing Hearts defeat

The loss was Celtic’s third on the spin and the first time they have been beaten in an opening league game since 1997.

It would, therefore, be easy to start losing some belief.

Because, make no mistake, Celtic fielded a team capable of beating Hearts. They also, eventually, created enough chances to score more than the Jambos did.

Some individual qualities may be lacking so far but the players are trying to play the way Postecoglou wants them to. Why else is Callum McGregor frequenting wide areas? Or Anthony Ralston and Greg Taylor regularly popping up in central midfield? The problem isn’t necessarily the system Celtic are trying to play, as much as some of the players they’re trying to play it with.

Is that on Postecoglou? Should he be adopting a more pragmatic approach, at least until he has the right men for the style he wants the team to play? Potentially. But the Celtic board knew who they were appointing and what he would try to do. Not giving him what is required for that quickly enough is on them.

This is a man, after all, who is routinely described in conflicting ways. He’s stubborn, but inspiring. Intense, but positive. Prickly, but entertaining. He is always, however, described as someone “who believes in what he’s doing”.

"I would rather put the principles in place," he said when asked about the lack of new recruits. "This is how we want to play football, and as the players come in, we will keep growing from that rather than go for any short-term measure that might get us over the line. It’s just not the way I ride."

So Postecoglou was never going to go down the pragmatic route, no matter how short a time and regardless of the personnel he inherited. The board must have known that.

But still, if Celtic lose games that they should win, even with the squad not quite ready yet, Postecoglou has to shoulder some of the responsibility. And it seems like he can accept that, as long as his players believe in what they’re doing. It's a process.

"It takes time, it takes training sessions, it takes games," Postecoglou said after the Hearts loss. "At the moment we're throwing teams together, I am anyway, and that's affecting it.

"But put that all aside, because that all sounds like excuses even as I'm saying it. It's still a game we could have won."

He has said more than once that his intention is, essentially, to give his players “the tools they need” to play in his system. What that doesn’t mean is that they are there simply to carry out his instructions robotically.

Postecoglou obviously wants them to try to play in a certain way but – particularly when he has spoken of “not being able to shield them” from criticism – he wants them to know they still have the agency to adapt and even deviate from the gameplan if the situation calls for it in the moment. It’s logical. It’s a two-way street: he has to believe in them as well or it doesn’t quite work.

So, yes, belief is a funny concept.

There’s no real way to measure it. You won’t find a way to truly quantify it in match statistics, you won’t physically see it when someone’s playing a pass and you can’t unequivocally tell if someone possesses it to their very core.

But, sometimes, you can feel it.

READ MORE: A tale of two keepers as John Souttar rocks Celtic and Tynecastle to their foundations - Hearts 2 Celtic 1

It’s still there in the stands, even after three defeats in a row. It’s still there in the manager, despite his obvious disappointment with the results. It’s still there in the players, regardless of the fact some of them are falling short individually at key moments.

It would be nice if you could feel it in the board.

At that same fan media presser when Postecoglou spoke of belief and bravery and creating special things, sitting right next to him was CEO Dominic McKay.

The chief executive said that day that he wanted to “go hard to make sure we have got success” and that bringing in the Australian was a “key thing” he had got actively involved with. Postecoglou is, for all intents and purposes, McKay’s man.

It’s one month today since McKay fully succeeded Peter Lawwell in the top job. That's a long time in football. The time has come for him to "go hard" and properly back his man. The time has come for McKay and co. to show the fans craving special things that they truly believe in Ange Postecoglou.