Barbara Hepworth's inner life remains something of a puzzle, but a new exhibition sheds fresh light on this leading modern sculptor, finds Ruth Guilding.

Since the Hepworth Wakefield art gallery opened in West Yorkshire in 2011, the small, indomitable figure of Dame Barbara Hepworth (1903–75) has been inching into the limelight. The Tate’s retrospective, the first in London since 1968, now hoists her into pole position as an international player.

Hepworth seems to have been rather a chilly woman, who set ambition and vocation above all else. Her legacy is a complicated one, intruded upon by a quorum of males: her husband, Ben Nicholson; her rival, Henry Moore; the influential critic Herbert Read; and the son-in-law and former Tate director appointed as her biographer, Sir Alan Bowness.

Hepworth’s considerable achievements in the male-dominated 20th-century art world have proved a conundrum for feminist art historians, for, despite being a key player in a thin field, her archives have remained largely closed and her biography unpublished. The resulting information deficit has only fuelled speculation as to what she might have had to hide.

With this exhibition, more of her papers have been opened to the Tate’s researchers, but much of what they have gleaned and presented here confirms what was already clear, namely the sculptor’s determination to control her image and the way in which her art was seen and understood, a control that her estate still exerts.

However, one strand of the new research presented in this exhibition stands out: early in her life, Hepworth was a Christian Scientist, a seeker after the ‘higher thought’ and ‘the true spiritual nature of existence’. The teachings of Mary Baker Eddy brought her to see the process of abstract creation as a means of transcending the petty problems of ‘mortal mind’. For a time, this was a bond with Nicholson, whose first wife, Winifred, had inducted him into Christian Science, too.

In 1932, Hepworth told him: ‘You know that Science Thought as I know it is the very core of my being the lovely genesis of perfect creation and unfolding of spiritual ideas. How beautiful it has been working with you dear.’ When her idealism began to grate on him, she reprimanded: ‘Surely we ought to be perpetually seeking the Truth together… if you won’t listen, or disapprove, you suffocate the mainspring of life itself.’

Although, later, she would variously refer to herself as an Anglican Catholic and an atheist, her commitment to spiritual principles is made clear here as a major guiding force for her work. This brings us to a closer understanding of the strict perfection of the forms that she crafted, such as Discs in Echelon, carved from dark wood in 1935 and cast in bronze in 1959.

Hepworth was decidedly high-minded, preferring ideas and ideas men to other people. She was interested in progression and modernity, utopias and nuclear physics. She collaborated and corresponded with a succession of alpha males the surgeon at whose invitation she made numerous ‘hospital drawings’ of operations, showing the connectivity between hand and mind; the Secretary-General at the United Nations Dag Hammarskjöld (memorialised in her sculpture Single Form); and the avant-garde composer Michael Tippett.

She meant her work to express the same idea of pioneering modernity. Public records and photographs of herself and her art were closely controlled and manipulated and she was the author of her own A Pictorial Autobiography, narrating a life of progress in flat, schoolgirl prose, as telling in what is left out as what was included.

But artists even high-minded ones are as human and venal as the rest of us. In 1939, when Moore was already sculpting monumental pieces for parks and piazzas, Hepworth, her reputation overshadowed by his, was still the prisoner of domestic timetables and small studios. She collaged photographs of her maquettes into pictures that presented them scaled up to optimum advantage and established in Modernist landscape and architectural settings, combinations that existed only in her wistful imagination.

Her driven idealism sat uneasily with the roles of mother, lover, employer and committee member at the Penwith Society of Arts in St Ives. The nearest this exhibition brings us to the personal is with her photograph albums showcasing the honeymoon period of her early years with Nicholson, when life and work were integrated their first holiday in Happisburgh in 1931, their works in dialogue and the reciprocity between her carvings such as Mother and Child (1934) and Nicholson’s painted and collaged works shown in their shared Hampstead studio, and the Hepworth-Nicholson triplets born in October 1934.

Human vulnerability is part of the story of the history of art; Van Gogh’s entire oeuvre, the tapestries made by Tracey Emin or the late gouaches of Roger Hilton would be incomprehensible if the trials that brought them to birth had been expunged from the record. However, the challenges of personal relationships and her drinking in lonely old age are left out of this account.

During the 1940s, Hepworth carved Wave (1943–4), one of a series of stringed and coloured sculptures in wood that tuned into the St Ives landscape. But, from the mid 1950s, as love and child-rearing receded, she could step unencumbered into a new kind of freedom.

As a single, middle-aged woman, she secured fame, commissions and the studio and assistants that allowed her to progress from carving to casting monumental pieces in bronze that could be sent around the world and reproduced in multiple editions: Single Form (1961–4) for the United Nations Secretariat in New York, Squares with Two Circles (1963) and the ‘Family of Man’ series (1970). When she was awarded the Grand Prix as our national representative at the 1959 Saõ Paulo Bienal, she knew she had ‘arrived’.

Hepworth’s output is well known, but even after this celebratory exhibition, which shows her work alongside that of important contemporaries and peers and crowns her with fresh laurels, the woman behind it remains a puzzle from which certain pieces are missing. We can only guess at the private fears that assailed this intense, rather lonely mistress of stone, wood and bronze, who felt compelled daily like some mythical creature to build the New Jerusalem, reveal the divine and populate the landscape with forms of pure, lapidary geometry.

‘Barbara Hepworth: Sculpture for a Modern World’ opens today at Tate Britain, London SW1, and runs until October 25 (020–7887 8888; www.tate.org.uk)