This is partly a matter of noticing, moment by moment, what is happening to the mind as a work takes shape. Through such observation, we may learn to exploit the plasticity of the brain. The potential for training this subtle capability is the subject of much interest among neuroscientists. One of the major steps in developing it, Brophy says, is the recognition that consciousness plays a more passive role in creative endeavour than conventional wisdom leads us to assume. Indeed, a kind of trained passivity is essential to the working process. Those who understand it ‘are aware of a quality of waiting which is something like waiting for a tennis ball to be lobbed out of a fog’.

As a poet, Brophy has a fine instinct for the nuances of metaphor, and this one expresses the paradox involved in being able to see only one end of the game we are playing. Psychoanalysts want to bring the mystery player into view, subject his or her tactics to scrutiny, and provide a régime of coaching designed to give consciousness the upper hand. For poets and artists, the fog itself has a certain presence, and the purpose of the game is to encourage the emergence of ideas, images and forms from its deeper recesses. So, Brophy argues, consciousness ‘must be managed in new ways’ and metaphor must be understood as integral to the operations of human thought. He proceeds to review a wide range of theoretical speculation about conscious intention, and the delusion of its centrality.

Freud is an obvious reference point, and Brophy focuses on a 1907 essay, ‘Creative Writers and Day-dreaming’, which argues that the writer’s hand is always steered by unconscious imperatives towards wish fulfilment. The contention that we can never directly experience ‘the most powerful motivating and shaping energies in our personalities’ also has implications for the way human lives are portrayed in literature. J.M. Coetzee’s character Elizabeth Costello is perplexed as to how we can know what we believe in, even when our beliefs seem to be steering our actions with fierce conviction.

The classic philosophical debate over free will and determinism is modernised through an inverted perspective on the topography of the psyche. Lacan called it the Copernican Revolution, since it involved the displacement of the ego from the centre of the universe to an orbital course on the periphery of some much larger, more powerful and less knowable planetary body. An associated line of approach to this kind of insight is drawn from the work of linguist Ferdinand de Saussure, who challenges the assumption that thought is in control of language. Without the support of language and all its pre-existing structures, he says, ‘thought is a vague, swirling cloud’. Which comes first, the idea or the words in which it is expressed?

In creative work with language, what certainly comes first is the heritage of literary forms. As Harold Bloom argues, this anxiety of influence from the past, and the need to claim originality through the overthrow of a precursor (a twist on the Freudian Oedipus complex), may be one of the main unconscious drivers at work in the brain of the writer. Theories also have a heritage, and Brophy links this one back to Aristotle’s discussions of mimesis, then moves forward again to a modernist framework to explore T.S. Eliot’s pronouncements on the inevitability of influence and imitation, and John Cage’s wholesale commitment to randomness.

Perhaps inevitably, the theoretical sections in the book read a bit like lectures, but they are good lectures: lucid, purposeful and with a warmth of tone that arises from personal involvement in the play of ideas. Conceptual exegesis is skilfully interwoven with close analysis of poems, so that the literary focus remains to the fore. The theoretical guided tour is not an end in itself, but a context for the articulation of Brophy’s own observations of what happens when a writer is at work. While he or she may not be wholly in control of the unfolding forms of expression, consciousness and personal determination are essential to the process. At every point, options are being negotiated and decisions being made.

The central hypothesis offered in the book is that there is an analogy between the way natural selection works in evolution, and the way creative expression takes form. Brophy seeks to demonstrate ‘that art brings us to the core of our being, for it manifests and expresses evolution itself – in all its glorious uselessness, excess and creativity’. Intertextuality is a mosaic, like the gene pool, in which random mutations and variations are constantly being generated; some are selected, reinforced and disseminated, and the rest are merely isolated manifestations. The tricky aspect of this thesis is that it straddles the divide between free will and determinism. The theory of natural selection is essentially deterministic, as it depends on the principle that evolutionary change is driven by the struggle for survival, in association with a hardwired instinct to pass on the genetic pattern of the species in its optimal configuration. But as Brophy repeatedly emphasises, creative work is not random: a writer or artist makes choices, and does so in a continuous and sequential way, to incremental effect.

The question then becomes, to what extent are these choices born of free will and conscious decision-making? In classic philosophical terms, the dualistic alternatives are stark: on the one hand, a view of the human artist as a blind watchmaker, merely combining and recombining from randomly available components until a pattern emerges that becomes self-reinforcing; on the other, an account of the creative process as a sequence of decisions and choices governed by overarching intentions. Brophy attempts to negotiate a course between these, by illustrating how selection and randomness are equally important in creative work. To revisit the metaphor of the tennis ball served by some invisible agency hidden in the fog: tennis must still be played and service returned, with all the skill and determination the player can muster, but the continuation of the game depends on the mysterious opponent, whose shots provide the scope for responsive moves that may be inventive and original.

Brophy’s hypothesis fights shy of the outright determinism in the theory of natural selection, which has no place at all for decided innovation, and this is where the metaphor breaks down: the human artist doesn’t operate in a fashion that is analogous with the process of natural selection. Nonetheless, I am engaged by Brophy’s analysis and relieved that he avoids the didacticism characteristic of so many evolutionist accounts of cultural phenomena. There is no glib attempt here to provide some definitive explanation of art. The book is the work of a subtle poetic intelligence and, in accordance with its thesis, plays strategically on the edge of dimensions that are acknowledged to be unknowable.