Patriotism was one of the virtues that made Rome great. Unless many Roman citizens had believed in Horace's classic expression of patriotism;

the glory of Rome could never have been. The sacrifices of an ordinary legionnaire were probably not as great as they seem to modern eyes. Life in the ancient world was short and cheap. For most soldiers, their alternative life was almost as squalid and uncertain and far less glorious.

It is easy to understand the patriotism of a Roman at the height of the Empire. The whole world admired its superior technology, discipline and order. Yet the patriotism that preceded the glory was what really changed the world. Just as it was the patriotism of soldiers and sailors from a small island state - a much-despised renegade in Europe - that built the greatest empire the world has seen.

Patriotism is most noticeable when a nation is great. Today the word reminds us of Americans, hand on heart, singing sentimentally before "Old Glory". But that is not when it is most important. At its best, it is the glue that holds a nation together. Nor is it a primitive question of blood and soil. Polish patriotism held the nation together even when the country itself ceased - for a while - to exist.

A true football supporter trudges loyally to the match even when his team is on a decades-long losing streak. The belief that Liverpool fans have sustained for so long, for example, made this season possible. It is the patriot’s belief in his country's potential that keeps alive the possibility of its success. This may (like the faith of the football fan) be founded on past glories, but must not entirely depend on them. There would have been no past glories without preceding belief.

Nor is it a question of hatred of others. A German patriot and an English patriot can be friends, if each acknowledges the rationality of the other's belief in his country. You do not need to despise Goethe to love Shakespeare. You do not need to deny another's right to be proud of his country in order to be proud of your own. Patriotism is the national equivalent of self-esteem, and is just as much a prerequisite to (and no more a guarantee of) success.

Trust, even though often misplaced or betrayed, is the key to success in any collective endeavour. Only if you can find people you can trust (and who can trust you) do you have a chance of achieving such goals. Patriotism is simply a kind of extended trust that allows you selflessly to strive for the greater good of people you don't know. Of course, as with the common or garden variety of trust, you will often be wrong. But you will achieve nothing without it.

Nothing in this life is purely good, however. Patriotism is a kind of love, and is as liable to be perverted as all other kinds. It is also as likely to be exploited. Most threats in history were exaggerated - or even fabricated - by politicians to cement their own power. They do these wicked things because they work. If he can persuade the people to focus on a national threat, real or imagined, a politician can exploit honest patriotism. Someone who feels profoundly that he should, if necessary, die for his country is unlikely to baulk at lesser inconveniences.

Therein lies the danger. Like all powerful forces, patriotism can be turned to good or evil. All who acknowledge it in themselves must be aware of that. That electricity can kill you is no reason to forswear the use of it. It is a very good reason, however, to be aware when enjoying its benefits of its dangers.

To be continued.