Watched the final of the Copa del Rey, Spain's big football knockout tournament, last night. It was between Barcelona and Athletic Club of Bilbao: Barcelona won, after a first twenty minutes of such frenetic brilliance that they scored three goals. Now, I've never been any kind of football fan, but living here near Barcelona in the years when el Barça has been performing a kind of beautiful athletic ballet has turned me (and, more remarkably, my wife) into dedicated Barça fans, into culés. But I still don't really understand the passions and fanaticisms that sport can inspire. Two examples related to this match …

After the final whistle blew, and the TV cameras panned over a roaring sea of Barça fans exulting, leaping up and down, and waving anything they could find with the Barça colours, there were also shots of Athletic Club fans in tears. Of all ages, girls and boys, men and women, with quivering lips, wet cheeks, fingers shrouding their faces. To see such naked grief and pain was very moving, but still … “It's only a game”, I thought. But the emotions were obviously real. The Athletic fans had been dreaming for weeks of the fantastic moment when their team would lift the cup, and they would all cheer ecstatically, and the world would be all right and everything possible – and that dream had died. When one dream dies, all other dreams seem a bit less possible.

Another aspect of the Barcelona–Athletic match was that the two teams embody political divisions in Spain. Barcelona is the 'national' team of Catalonia, and Athletic is the 'national' team of the Basque Country – and many Catalans and Basques have dreamed for years of independence, of their homelands being separated from Spain. These nationalist ambitions clash directly with what has been called 'Spanish nationalism': the movement which would like to see a much more centralised Spanish state, run from Madrid.

This political dimension of the game was emphasised when Esperanza Aguirre, right wing boss of the Madrid region, made a suggestion on a radio programme a couple of days before the match. She predicted that, when the Spanish national anthem was played, there would be boos and whistles (“una pitada”) from all the Catalan and Basque fans in the stadium. If so, she insisted, the game should immediately be stopped, the stadium cleared, and the game played at a later date – with no spectators, thus avoiding disrespect to the Spanish state.

This interesting suggestion (OK, provocative) caused a predictable storm of protests, and presumably gained Aguirre bonus points from the far right. Equally predictably, there was an even louder pitada than might have been expected … and then everyone got down to enjoying the match. The unity of Spain was not noticeably damaged – indeed, may well have been reinforced, given the excellent relationships between the two groups of fans, revelling in the best of Spanish football.

I think it was the Liverpool manager Shankley who said, many years ago: “Football's not a matter of life and death – it's more serious than that.” What exactly is it about sports that touches so many people so deeply? Is sport actually a form of theatre – in which we see our deepest hopes and dreams symbolised, and in which those hopes and dreams can really triumph or really fail?