At its most immediate level, Peter Brook's Threads of Time is an accessible and hugely enjoyable mapping of the personal and professional evolution of one of this century's most consistently imaginative and indefatigable directors. The book is part critical reflection on a body of work that includes over 70 productions and a dozen films, part restless quest in the guise of travelogue, part philosophical enquiry into the nature of what psychologist James Hillman has called "soul-making''.

Structurally, it employs a chronology that freely accepts digression, like memory itself. Part One covers the first three decades of Brook's life from his birth in London in 1925; here Brook details his earliest memories of the allure of illusion in theatre and above all film, and his hyperactive apprenticeship in a variety of styles and contexts. Part Two takes us from Brook's growing scepticism towards the genteel fictions of an escapist, image-based aesthetic in the mid-1950s, to the white-walled playground of the joyously airborne A Midsummer Night's Dream, his swansong with the Royal Shakespeare Company in 1970. Finally, in Part Three, Brook describes his work in Paris with his international group, from exploratory research journeys in the early 1970s, to recent forays into the fantastic inner landscapes of neurological disorders (The Man Who..., Qui est la?).

On a secondary level, this is a book of sources, an acknowledgement of teachers, influences and primary collaborators. To paraphrase the title of the G.I. Gurdjieff autobiography that Brook made into a film in the late 1970s, Threads of Time might well have been subtitled "Meetings with Remarkable People''. Over the past 50 years, Brook has worked with a bewildering array of artists, including some of the most acclaimed performers, writers and designers of post-war Europe, as well as the infamous, dissident, and eccentric: Satanist Aleister Crowley, Jean Genet, Salvador Dali. With a great deal of compassion, humour and relish for the telling anecdote and the arresting paradox, Brook reflects upon encounters that engendered creative frictions and combustions, flashes of re-cognition that unsettled, encouraged or energised. In particular, he offers some rare insights into his extensive study with two of the heirs to Gurdjieff's legacy, Jane Heap and Jeanne de Salzmann, and the gradual, inevitable interweaving of this private work with his public output as a director.

In terms of his theatre practice, Brook provides perceptive discussions of the evolving specificities of its deep grammar: rhythm, the nature of "presence", the radical heurism of improvisation, research as self-research, the centrality of direct experience and of collective work to the actor's individuation, and so on. In addition, he offers illuminating perspectives on the "transparency'' he admires in those actor-collaborators he deems to have gone beyond ego-driven virtuosity to a psychosomatic integration. Paul Scofield's "alchemy of the imagination'' in the incarnation of an internal image-action, Glenda Jackson's "instant complicity'' and quality of attention, Jeanne Moreau's revelatory fluidity, Yoshi Oida's "making an emptiness": for Brook, all bear testimony to an embodied transformability, a sensitised capacity to articulate and distil the trajectories of inner impulses in external forms.

̽»¨ÊÓƵ

Brook reiterates here a perception he has often made regarding the unstable relationship between surface forms and the underlying impulses that "inform" them: in other words, between means and meanings. He suggests that many of his theatre productions possess two distinct, if closely interrelated, aspects. First, the external mise en sc ne comprises contextually determined forms emerging from the performance's physical conditions. Second, beneath these specific patterns of images, no more than tips of invisible icebergs, lies what he terms "the hidden production: an invisible network of relationships'' that can give rise to other forms and patterns without forfeiting its "essential meaning''.

Brook's neo-Platonic formulation of an originary core underpinning multiple and relative phenomenal possibilities provides a useful lens for reading beneath the surface of his autobiography. It brings into relief what seems to me to be at the heart of Brook's project here: through the lightest of touches over the topographic contours of a life remembered, to apprehend what classical Chinese philosophy called li - the principles of an organic order subtending the chaotic markings in jade, the grain in wood, the events of a biography. Brook contends that such order is accessible through "mathematics, geometry, art and silence''.

̽»¨ÊÓƵ

Inevitably in a book of such breadth of scope, there are occasional blindspots that will cause some readers to baulk. For example, in his account of the detailed study of documentary source materials for The Ik in the mid-1970s, there is something rather disconcerting in the dispassionate, decontextual formalism of actors honing their observational skills by poring over the minutiae of "how the shrivelled body manages to propel itself forward, or what muscle enables a near-atrophied arm to lift a cupped hand filled with water to the lips''. As Kenneth Tynan pointed out at the time, the net effect is for the reality of these starving Ugandans to recede as it is translated into a kind of saturated naturalism for hip, Parisian theatre-goers.

However, such infelicities are rare, and the book as a whole will provide practitioners, teachers and students with substantial food for thought. Ultimately, Threads of Time attests to the fact that Brook's gradual transformation from post-war British theatre's enfant terrible to contemporary European theatre's eminence grise has entailed no diminution of inquisitiveness, energy or focus. Quite the reverse. For this most pragmatic of humanists has found ways to understand and inhabit the paradox of innocence and experience - not as entropic slide towards disillusionment, but as self-regenerative cycle and insistent wake-up call to look, listen and immerse oneself in the contradictions and possibilities of life's every moment.

David Williams is visiting professor of theatre, Dartington College of Arts, Devon.