What is acting for? At its very centre, theatre is a form of storytelling. Every kind of society has its web of stories. How they are told, by whom, to whom, in what ways – these will be different in every culture. But for each, story telling is often to be found at the core of the community, at the heart of people's identity and sense of belonging. In our own, theatre can be the place where we come together, reaching with and through stories, to who we are and to who we can be.

If you were to put a big banner over the door of the theatre, it would read Come to Recognise and be Recognised. At the moment when a good piece of theatre comes to an end there's often a collective exhalation, and you know that many people there have somehow felt recognised, or that all who are there have recognized each other. We have seen and felt and perhaps have examined our common experiences. What has happened is a sort of hybrid between the story the actors are telling, and the story the audience are receiving, interpreted by their subjective responses and personal histories. For these reasons I think that at its best, theatre has the potential to breed compassion, understanding, and tolerance. If you can understand why people do what they do, perhaps you will be more generous. You may leave the theatre a little more tolerant, slightly less ready to judge. I think that this sharing of experience, this process of mutual recognition, is among the most poignant and vital kinds of communication. Hence that exhalation, that sigh of understanding.

My own route to acting came from a realisation that I wanted to be part of this communication. I didn't become an actress because I'd spent afternoons at the cinema watching Katherine Hepburn or Julie Andrews; it wasn't anything to do with movies or television, because where I lived we didn't have any of those. But when I was about nine years old I picked up a difficult poem by W.H.Auden, and read it inside my head. And I found that I was full of a desire to read it aloud to people. It was a complicated love poem from – I know now – one man to another. However much or little of it I was able to understand, whatever meaning I sensed within the words, I just felt very strongly, very powerfully, that I wanted to be the person who communicated that meaning to others. I could understand some of it just through the rhythm of the lines, through the sounds and shapes of its language, and I wanted to feel that language pass through me. I wanted to be the conduit for somebody else's experiences, filtered through me, and passed on to other people. Which is the job description, really.

This passion, though incoherent and unrealised, stayed with me. And then when I was 15 I was taken to Stratford for the first time, and I saw Richard II played by Ian Richardson. It was a kind of epiphany – I walked in as one person and walked out another. I saw that production 6 times, identified obsessively with Richard II and learnt the whole role off by heart. The language of that play lit a fuse wire of some sort, and it was then that I knew I wanted to act.

I got a place at drama school, but for the first term and a half I found myself flailing. I had no real confidence, and couldn't seem to cohere the various classes in physical and vocal technique into anything that felt like acting. Other students seemed to have a much clearer grasp of what they were doing than I did. Then well into the second term, we started work on Antony and Cleopatra, with the part of Cleopatra broken up into three chunks. I had the scene where Cleopatra, hearing from a messenger that Antony has married Octavia, goes crazy and vents her grief and rage on the poor news-bearer. It's a scene of volcanic volatility, requiring mercurial emotional power and range. I was 18 years old and very inexperienced – in almost every way. What did I know of the forces that fuel Cleopatra? And yet here I was, groping my way through the scene, the whole class standing around watching. We had a very tough director, and suddenly he stopped the rehearsal, and let rip. "Juliet, this is beyond hopeless. This is sexless, passionless…"

I stood alone in the middle of the room as he tore into me, consumed with the pain of it, wretchedly exposed. In the fog of my misery I was conscious that I had urgent choices to make – collapse in a sobbing heap? Run out of the building and under a bus? Apply for medical school? And then, suddenly, I just filled with rage. He told me to start again, and I did. And I felt this fury pounding through my system and out through the language. Something bio-chemical was happening to me - my own outrage and humiliation mapping on to Cleopatra's, her feelings in my veins, my feelings in her words. Everything began to fall into place, and – for the first time as an actor -I could sense that magical silence of an audience that has been reached and touched and held.

After that day I didn't look back. Of course there were many ups and downs (there still are), new directions and old setbacks, but a door had been kicked open. I saw that this is what you have to be and do; everything you think and feel has to fuel the work; you have to be right inside and underneath the words. You take the text and you burrow downwards from its surfaces towards the roots of the person you're playing. You draw on everything you have experienced in order to understand the character, the forces that drive them, their history, the ways in which they interact with others, so that the audience can understand them too. So that you can achieve those exhilarating moments of collective understanding.

I often wrangle with myself as an actor, and wrestle with the process. In striving for authenticity I often have the feeling I am falling short. It isn't very often that you can say to yourself that a piece of work has been fully realised, this is what I dreamt of when I read the script. But when it does work, when there is none of the distracting and irrelevant ego, no competitiveness, no silliness, just the play, just working together to communicate the story to the audience, when it is like that, then for me, acting exceeds everything.

• This article was amended on Wednesday 13 May 2009. The article above we published by Juliet Stevenson, on the experience of acting and the role of theatre, failed to include numerous revisions which she had made. The text as she intended it now appears under its original headline.