The latest edition of When Saturday Comes magazine contains a feature on the rivalry between Derby County and Nottingham Forest that absolutely nails the theory behind local derbies.
The piece argues that the main reason Forest and Derby fans don't get along is not their differences but their similarities, something that has to be true of all other footballing rivalries.
For example, Manchester United and Liverpool in this country and, in Spain, Real Madrid and Barcelona supporters are united by their thirst for honours, to be number one.
The greatest football rivalry of them all, that between Celtic and Rangers, obviously has its roots in religion and politics, but what it boils down to is just one set of working-class blokes holding another up as their nemesis, and vice versa.
Moving swiftly along, then, from games in front of fervent 60,000-plus crowds to last week's fixture at London Road, where the visiting supporters did the team proud and the players responded by showing some encouraging signs against a very good Posh side.
If Peterborough can keep hold of Craig Mackail-Smith and Aaron McLean they will be threat to defences in the Coca-Cola Championship next season, just like they have been at this level this time around.
I maintain, though, that if you transferred that front two to just about any other team in the division, they would make an impact. George Boyd is a decent midfielder but the chances Mackail-Smith and McLean get are almost entirely self-generated, through their sheer hard work and persistence.
Of course, they are good players too, because you don't score bags of goals just by running around, but their marriage of high skill and industry is one made in heaven, and one which usually leads to lots of wins.
To go back to the question of supporters after that brief tangent, though; having the privilege of being situated in away grounds in the press box means you will get to gauge opinions of the other team's supporters, usually in the queue for the pie bar of the half-time toilet dash.
And guess what? Listening to Peterborough fans is, but for a slight inflection in dialect, just like overhearing their Cobblers counterparts at Sixfields. Their concerns are the same, even if they have got a currently better team.
They are worried about the form of key players, refereeing decisions, the short-term future for the club, and what's happening with the ground. Most have opinions on players, and the majority of them are negative.
So Cobblers supporters should not begrudge their Posh rivals this moment in the sun. Because, frankly, there really isn't that much to separate the two groups and the balance of power in football is constantly changing.

Wayne Rooney copped some stick last week for saying in the build up to the Manchester United-Liverpool game that he 'hated' Liverpool FC, but I think it was a fair enough comment.
Okay, so Rooney may not be the most media-minded young man and you're unlikely to see him doing the stuffed-shirt ambassadorial stuff that David Beckham likes to, but there's nothing wrong with a player speaking his mind.
Only problem is, he almost certainly doesn't hate Liverpool FC. I'm willing to bet upwards of a pound that he's got mates who are Liverpool supporters, maybe even family members.
It made a nice line in the newspapers, though. And no doubt helped to fire up the Liverpool players ahead of the game, which they won convincingly 4-1. Maybe that's what his manager was so upset about…