Robert Henry Rundle Clark, antiquarian bookseller: born Birmingham 31 March 1951; married 1984 Jane Nellist (one daughter); died Oxford 1 January 2003.

Devotion to a spirituality derived from Sufi mysticism and running an antiquarian-book business specialising in English books printed before 1800 might seem a strange, even contradictory, combination. But to Robert Clark they were neither strange nor contradictory, and to both, as in everything else he touched in a life too short, he brought his own particular gift of quiet certainty.

He was born in Birmingham in 1951, the second child of R.T. Rundle Clark, the Egyptologist. As a child he suffered from scoliosis (curvature of the spine). The condition is not uncommon, but in his case it was worse than usual, and no amount of medical treatment could cure it. He bore it even then with fortitude, but it was to be an affliction of increasing severity.

It did not prevent him from getting a good education, first at West House Preparatory School and then King Edward VI High School for Boys at Edgbaston, from where he won a scholarship in English to King's College, Cambridge. There, in the normal course of events, he would have taken his degree, and it would have been a good one, in 1972. But, as for many of his contemporaries, the conventional path spread out before him seemed deeply unsatisfactory, and he chose to leave Cambridge early.

Clark was a deeply spiritual person, although not religious in the accepted sense. His search for alternatives led him in his early twenties to the Beshara School of Intensive Esoteric Education, a non-denominational educational establishment offering a programme of study based on the principle of self-knowledge.

He was a lifelong gardener with a special love for growing vegetables, and this provided him initially with a livelihood. Books and printing were another interest; he learnt the craft of printing in his late twenties and worked for two years at the Beshara Press in Sherborne, Gloucestershire. In 1982 he got a job at the Oxford antiquarian booksellers Sanders, and it was the two years that he spent there that led him to discover his métier. He set up on his own as a bookseller in 1984.

The Beshara School, meanwhile, had been founded by Bulent Rauf in 1973, at Chisholme House, near Hawick, on the Scottish Borders. The 18th-century house was near derelict, and it took two years to restore it, but from 1975 the school, now called the Chisholme Institute, began to take in students. Many hundreds have come to it in the years since, to listen to Rauf's teachings and absorb the texts of the great Andalusian mystic Muhyiddin Ibn Arabi that he translated.

Robert Clark was closely involved from the outset. His own exploration of the Western traditions of mysticism struck a chord with the Beshara programme. He was for many years a trustee of the Beshara Trust. He was manager of Beshara Publications and an active participant in the Muhyiddin Ibn Arabi Society, organising its first six annual symposia between 1984 and 1989.

How did he combine this with his bookselling business? It was, like his own survival of his disability, little short of a miracle. After two years in London, he moved to Oxford. His premises were at 6a King Street, a quaint two-storey building in Jericho. He worked and kept his stock on the upper floor (but with a door on the street), where he received customers by appointment and whence, from time to time, he issued catalogues.

No one who got them will ever forget those catalogues. They tended to specialise in English literature, history and theology of the 17th and 18th centuries, with an occasional earlier book, and an assortment, eclectic and never dull, of later books. He had a special affinity for the 17th century, perhaps because the boundaries of the subjects of its books were less defined than later, perhaps because so many of the mystical impulses that moved him flowered then.

How to recapture his physical presence? His body, meant to be some six feet high, shrank to five and a half, but you hardly noticed this, since his face was so immediately captivating. He radiated a kind of warmth and assurance, behind which was a firm sense of purpose; once he had made up his mind, nothing would change it. He broke his hip in 1995, and osteoporosis was added to his tribulations, but he never complained.

He died on New Year's Day and is buried at Chisholme. Volunteers have been replanting the lost forest around it – so far 17,000 trees have been put in.

Nicolas Barker