Often when we question our capacity for suffering, we wonder at the extremes of pain to which individuals are sometimes subject.

And in our minds we see not the person who is bearing the pain, but a measure of pain that is coloured by the limits of our own experience. The same is true of loneliness. For when we witness the grieving of a mother for the child she has lost to sickness, or the sadness of the abandoned lover, or the man who mourns the passing of his father, we are held in the palm of our own imaginings. The extent of another's loneliness is truly difficult to grasp.

What is the effect of loneliness? Well, often it drives us to join, mix with others, to be in company when we would really prefer it otherwise. You can see this a lot in first-year, when everyone feels that they have to go out in droves, rather than do things on their own. You can see it in the way that some people will not willingly enter a new activity without a companion at their side. How some are often reluctant to go to the cinema on their own, or eat by themselves in a restaurant. Even at Christmas, which is a time of tension for some families, people are very reluctant to be on their own... far better to bicker with relatives than to be left out of the family circle!

Although we are a gregarious species, much of our togetherness at a superficial level has to do with our reluctance or inability to be alone. Relationships are another example... it's sometimes quite difficult for a person to establish the amount of personal space that they want in an intimate relationship, time when each partner needs to be alone - not to feel lonely, but to enjoy activities that require solitude. It's particularly difficult for busy parents to establish that space, labouring against the common view that seeking such space is actually quite selfish.

Solitude feels very different from loneliness. There's a gentleness and a quiet sense of contentment about solitude which enables us to become immersed in a wide range of activities, such as reading, listening to music, painting, hill-walking and a host of other hobbies. It seems to touch on a basic need for peace and harmony. It allows us to draw on our sources of inspiration and creativity.

Fear of being lonely is one of the key issues in binding people together. It's particularly evident when a couple start to feel like going their separate ways. It's a fear of loneliness that often creates the eddies and backsliding, hindering a partner from saying, 'it's not working out. I don't wish to be in this relationship any longer.' And often, because our emotional life is coloured by melodrama, by a propensity to see things in black and white, we see the loneliness as fathomless, as much more acute than it could ever be.

We are all lonely to a greater or lesser extent... and yet how often do we hear the comment: 'Oh, she's quite a lonely person' as though we are defining a state that carries some explanatory and predictive value. And how often is it a way of stigmatising a person, and diminishing them?

None of us wants to experience the full extent of our loneliness, the extent to which each of us owns a unique and ultimately unshareable existence. We are all aware that we have aspects of ourselves that are not loveable, or accepted, or understood by others.

Many of us will entertain occasional fantasies in which some of our needs are met in ways that reality does not allow for... a world which tells us something about the extent of our loneliness and about how we are unable or unwilling to share with those around us in the full expression of our existence.

Often the extent of our loneliness is only evident in retrospect, when we are able - from the vantage point of a satisfying relationship - to look back on earlier relationships and discover how restrictive they were. So, for much of our lives, we existed in an emotional world that was relatively impoverished and lonely compared to what it became... at the time it was a bit like being unaware of what we were missing in our diet.

Our surroundings have powerful ways of reinforcing our loneliness. One example is advertising. What does advertising promise? Power, status, yes - but - more than those two - a 'feel-good' factor... buy this and you will feel better, happier, more secure and - not least - less lonely. Advertising is about making you feel that without the shoes, the shampoo, the clothes, etc., you will not feel part of the world around you... that you will be left out., that if you don't buy or cannot buy something then you're outside the magic circle. It is concerned with the child in us that wants to be included, wants to be part of what is going on... you have only to see the number of people eager to buy clothes with designer labels to realise what a powerful effect such insignia can have on their owners.

When we feel lonely, we lose that feeling of entitlement, that feeling of membership, that feeling of access to the benefits that a relationship automatically confers. Sometimes people will try to reduce acute feelings of loneliness and isolation by indulging in spending sprees, as if the possession of something physical could dispel the inner emotional pangs. So loneliness is not a simple thing, except in its powerful dynamic... there are many layers to it in terms of how we interpret our loss and isolation, and many powerful ways in which these are reinforced in our environment.

Loneliness is like sitting on a hill and looking into the distance, but not actually seeing much of the view... because a mist blurs the shapes on the horizon. Loneliness is such a powerful, primary feeling, and so at odds with our sense of emotional well-being, that it distorts all around it, making us unobservant and blind to those sources of support and comfort that actually lie close at hand.

Loneliness resembles entering a hall of mirrors and seeing the familiar as something that's made painful and scary. It's also like looking at a distant table - out of reach and piled high with delicious food - and feeling that in your hunger you could quaff everything in sight, forgetting all the while that you don't require that much to sate your appetite... when we are lonely we don't actually need much in the way of company to banish the feeling... that's why pets play such an important role in our lives, and yet the feeling can be so insistent that it seems like our life needs to be changed out of all recognition if we are to feel less lonely.

Another way of looking at loneliness is to turn the feeling upside-down and ask yourself, what would it be like not to be feeling lonely like this? Well, for a start it might involve a change of attitudes: you might share more of your life and be more generous in expressing your feelings, yours joys and sadness, be more open to the needs of others, freer with your time and efforts, and exist in a world in which giving not taking were the norm. You might feel more trusting and acceptant of other people.

The opposite of feeling lonely is not necessarily having another person in your life; it is about experiencing those feelings of openness, self-disclosure and acceptance that enable good relationships to exist. In fact before we can get near to sustaining deep and meaningful relationships we need to be confident in expressing and experiencing our feelings in ways that are modest but effective. We are often lonely not because we haven't got the right girlfriend or boyfriend, but perhaps because we have managed to cut ourselves off from others, and have lost confidence in our ability to relate in small but important ways to the world around.

Another way of looking at loneliness is to ask yourself how do you relate to someone else who is feeling really lonely? it's partly a matter of understanding and acceptance but it is also a question of establishing the necessary degree of trust to break down the barriers, to enable that person to open up and start responding, to help them realise that making a relationship - even a casual, small relationship - isn't necessarily going to involve hurt and disappointment. Very often our loneliness is a prison of our own making, in which we take for granted that the walls are thick and stretch to the heavens, emotional prisons that are girded with all kinds of misperceptions, casting the world around us in the role of a jungle with no clearings or maybe of a polar night devoid of stars.

Despite the hurts and frustrations in life, a loving, warm and intimate relationship is what most of us would wish for ourselves and others. And in that quality of relationship we see a particularly rich fulfilment of our humanity. A good relationship enables us to explore and experience a wide range of feelings. There is something lacking in a human being who has never loved, never hated, never grieved or felt alone. The range and depth of our feelings is the measure of our humanity. When we feel acutely alone, we are at our most human and most vulnerable. The length of shadow that loneliness casts on our lives is often a sign of how much else we are capable of feeling and sharing with others.

Loneliness can dwell amid great anguish in the inner recesses of our hearts, and we may despair of finding a way to change our feelings. Yet with determination we can endow most of our hopes and wishes with a great measure of reality. Loneliness rarely lasts, and its span is dependent as much on our wishes and the course of our convictions as upon the changing nature of circumstances.

It would be a capricious whim to dream of a world without loneliness, for that would deny us all those repeated experiences that carry important learning in helping us to value those whom we love and cherish. Our awareness of cold gives us a measure of heat. So it is with loneliness and the hand of friendship.