I found myself listening to a General, a man I greatly respect, addressing his troops. Among the things he said, one phrase stayed with me. I do not remember the exact words, but the idea was this: a soldier’s family is an integral part of his capacity to serve.

It struck me as a beautiful observation. And, as often happens with phrases that contain something important, I began to see the contours of that importance and found two distinct and complementary meanings. I do not know whether the General deliberately left open the question of which meaning he intended. Perhaps only the first, more explicit one. Perhaps both. Or perhaps the first for some and the second for others. It would have been a different speech for different people, at the same moment, with the same words. A kind of linguistic magic.

The first meaning is fairly evident. A soldier with a family behind him that supports him, understands his work and accepts his absences, his sacrifices and sometimes the risks he takes is probably a better soldier. He is more at ease, more focused, never alone. He knows that someone is waiting for him, that someone is taking care of the things he cannot attend to, and that someone shares, at least in part, the weight of his responsibilities.

The family, in this form, is a system that makes him better able to protect others.

And of course this can extend beyond the military context. It applies to a doctor, a teacher, an entrepreneur, anyone with a task to perform and responsibilities to shoulder. A family that works is an important part of the strength with which we face the world.

But there is a second interpretation, less immediately apparent, somewhat concealed by the compelling obviousness of the first.

What if having a family increased our capacity to serve not only because someone supports us, but because we have someone to be responsible for?

I am no longer talking about the family that helps us do our work better, that packs our rucksack or briefcase. I am talking about the family that changes the very meaning of our work, our choices and our presence in the world.

When you become a father or a mother, something changes. Anyone fortunate enough to have become one knows this. You do not become more intelligent, braver or better. There is no miraculous transformation. But your duties increase enormously, as does the direct importance of your life to other lives. And so the significance of your existence may increase too.

Before, you could afford to think chiefly of yourself, your well-being, your satisfactions and even your failures. Now there is someone who depends on you. Someone for whom you must provide more than just food, a home and an education.

You must also hand on to them a world worth living in. And then that world begins to concern you in a different way.

Justice, security, freedom, honesty and respect for others cease to be merely principles on which to hold an opinion. They become concrete conditions of the life of someone you love. The future ceases to be an abstraction, because it has a face, a name and a date of birth.

I am not arguing that people without children are worth less, or that all parents become better people. That would be foolish. I am arguing something different: having someone for whom we are profoundly responsible can change the measure by which we judge ourselves and what we do.

A soldier with a family does not merely have someone who helps him serve. He also has another reason to do so. He does not necessarily fight better because he is more at ease. He may fight better because he feels more deeply what deserves to be defended.

And here the word serve becomes extraordinary. Because serving does not simply mean obeying an order or fulfilling a professional duty. It means recognising that there is something to respect more steadfastly and with greater commitment than we respect ourselves.

Perhaps the family, when it manages to be what it should, does precisely this: it moves us away from the centre of the world and, paradoxically, makes our presence in the world more important.