Right at the end of this exhilarating journey through a century’s struggles over the human body, Olivia Laing invites her reader to “imagine, for a minute, what it would be like to inhabit a body without fear”. This simple hope comes to sound like a radical demand for the impossible; after such a vivid catalogue of the many humiliations and cruelties a body can be made to bear, it isn’t easy to imagine.

Laing’s impassioned commitment to the promise of bodily freedom, of every body’s right to move and feel and love without harming or being harmed, shines through every sentence of the book. But she is too canny a writer to miss the rich and bitter irony in which efforts to realise this promise so often get caught: every movement to liberate the body comes to be marked in some way by the constrictive regime it’s trying to escape. The writer who best grasped this irony was the Marquis de Sade, of whom Laing writes with an open and compelling ambivalence. De Sade’s nihilistic fantasies of sexual torture are a discomfiting reminder of how easily the liberty of one individual becomes the enslavement and abasement of others.

But her central character is Wilhelm Reich, disciple of and eventual dissenter against Sigmund Freud, visionary theorist-activist of sexual politics in the Viennese 1920s and hapless, delusional inventor of the orgone accumulator in the American 1940s.

In Vienna, Reich had sought to draw psychotherapy away from Freudian analytic neutrality and towards a practice of liberation, whereby the patient’s “character armour”, coiled knots of psycho-physical tension, would be dissolved by touch, releasing (or, in Reich’s terminology, “streaming”) ecstatic libidinal flows through the body and restoring its availability to the full range of feeling. But an increasingly persecuted and grandiose mindset would eventually lead him to imagine that this same cure could be achieved by confinement in a tiny wooden cell emitting “orgone energy” to its libidinally depleted occupant.

It can seem as though all the great victories and tragic failures of modern sexual politics are concentrated in the figure of Reich. For Laing, his supreme insight – that the true source of the body’s power is the vulnerability we prefer to conceal – has never been more valid. In shutting down our vulnerability, we block access to the full range of our feelings, giving rise to the kind of mechanistic compliance favoured by fascism.

But what makes Reich’s tormented life so poignant is how, in striving to release us from the constrictive knots of the authoritarian mindset, he couldn’t help getting caught in them himself. As he aged he fell prey to pseudo-medical moralising, ascribing disease to blockages of orgone energy in his 1948 The Cancer Biopathy, while worrying in his 1953 People in Trouble about “biologically degenerate” forms of sexuality. Towards the end of his life, he turned down Allen Ginsberg for treatment because he was gay.

If Reich is somehow exemplary for Laing, he is hardly unique in his concerns. On the contrary, what she shows across many different lives and milieus, from Susan Sontag to Andrea Dworkin, 1920s Berlin to 1950s Kentucky, is how the urge to release the body from fear and prejudice is rarely free from ambivalence and contradiction. The theme is amplified by reflective vignettes of her own bodily experiences, woven into the book with a deftness, candour and generosity that readers of The Lonely City and The Trip to Echo Spring will immediately recognise.

In a series of dazzling forays into painting, Laing shows us how art illuminates the tension between the wish for freedom and “a counter-wish to clamp down, to tense up, to forbid, even to destroy”. Agnes Martin’s grid paintings of the 1970s induce a vertiginous rapture in their viewer, “an experience of being temporarily untethered from the material realm”. Yet this sensation of borderlessness is the effect of her grid’s tight cellular form: “Despite its liberatory effects, the grid is manifestly about control”.

Laing finds a much more explicitly political expression of this paradox in Philip Guston’s controversial Klan paintings, where a queasy horror before the unyielding, rigid “block” form of the Klansman’s hood mingles with an uneasy fascination for it. The hood’s shape is a violent defence against the gross materiality of the body pulsing beneath, “open and insatiable, helpless and dependent”.

This is an expansive book, bold in scope and speculative range, an invitation to ongoing conversation rather than bland assent. In that conversational spirit, I would venture a different view of the dynamic between freedom and control animating the book. Laing’s Reichian take on sexuality as a “wild force”, which every social order seeks to circumscribe and control, might account for why states and institutions keep such vigilant watch over the body, but not why liberation movements so often sabotage or compromise themselves – why, for example, an agitator for sexual reform such as Magnus Hirschfeld, founder in 1919 of Berlin’s Institute for Sexual Research, should also have been an advocate for “welfare eugenics”, including the compulsory sterilisation of the “mentally stupid”.

Reich, in other words, has a theory of suppression, of how the body is kept compliant by external forces; but he lacks its essential Freudian complement, a theory of repression, of the anxiety induced by the strangeness and lawlessness of the body’s drives and the unconscious mechanisms we employ to keep them in check. From my more Freudian perspective, fear belongs as much and as indelibly to us as to the police.

Yet Laing’s Reichian utopianism, with its ultimate horizon of a body without fear, coexists with a clear-eyed sense, at work in all its granular explorations of sexual politics, art and ideas, of how and why that horizon seems always to be vanishing. And this tension, between defiant hope and sober realism, only enriches her intensely moving, vital and artful book.

• Everybody: A Book About Freedom is published by Picador (£20). To order a copy go to guardianbookshop.com. Delivery charges may apply.