John O'Donohue believes there is a metaphysical crisis in Irish religion. As the Church has been tainted its parishioners have been deprived of "a fixed, idealised notion" of Christianity and what it means.

The crisis is too deep to be resolved by repackaging, he says, but there is hope: Ireland's tradition of spirituality. This, believes the writer and priest, is a tremendous resource for an age dominated by "instantaneity".

His latest book, Divine Beauty: The Invisible Embrace, is an attempt to reconstruct a system of metaphysics, a basic philosophy, for our times. It has not been easy. The book took three years to write, O'Donohue having to look through the "fractured lens of postmodern reconstruction". Through a shattered glass, though not darkly. He begins, after all, with beauty, not only as beheld but also as experienced.

The book draws widely on its author's experience of beauty, whether in art, nature or relationships, which became a moral compass. O'Donohue's approach emphasises the fundamental role that the sensual, or Eros, plays in our perception of beauty. The sensual, he says, has been repressed by Christianity even though it is not lost. So the book explores Eros as Eternal Echoes explored agape, or Christian love, and Anam Cara, his first book, explored philia, or friendship.

It soon becomes clear that O'Donohue's vision of beauty is heavily influenced by Romantic poets such as Keats, Wordsworth and Shelley in English and Goethe and Rilke in the German. Also influential are Donne, Herbert, Hopkins and Yeats, the man who described himself as the last Romantic.

But it is the philosophers Aquinas, Meister Eckhart and Plato who have been the greatest influence - above all Plato. From him comes the book's classical understanding of beauty, with an emphasis on symmetry, claritas and integritas. O'Donohue recalls the observation of the philosopher Alfred Whitehead that all subsequent philosophies were "footnotes to Plato". He is similarly appreciative of Plato's great medieval heir Thomas Aquinas. The book is trying, he says, to "revive that \ treasury of sensibility for a new context".

It is several years since O'Donohue ministered as a priest, because of "a fundamental conflict with authority". His bishop, in Galway, appointed him to a parish, but it would have meant giving up his writing. They could not reach an accommodation, and O'Donohue left. He then helped set up and teach a theology course at Galway-Mayo Institute of Technology.

Now he lives by writing alone. The irony does not escape him that as a contemplative writer who is frequently critical of consumerism, he makes his living by catering to consumers exploring spirituality. He says the huge success of Anam Cara, in 1997, took him by surprise. Besides Eternal Echoes, two books of poetry followed, Conamara Blues and Echoes Of Memory. He is now working on a long poem called Elegy For Priesthood and hopes to translate his PhD thesis, on Hegel, from German into English.

Divine Beauty is, he agrees, a contemplative work that explores matters he has been thinking about for years. It is "a companion to the oblique and unheard side", an attempt to satisfy what he sees as that "huge, almost haunted longing in the Western world".

As a man of faith, things metaphysical appear easier for him. He is, after all, someone for whom belief is "a fundamental intuition", even if within faith there are "journeys atheism would not believe". He also places great store by imagination. Of the hereafter, for example, he says: "If you imagine nothing there will be nothing. You inherit what you imagine is on the other side, including nothing."

... Patsy McGarry

• John O'Donohue will be talking about the book at the Burlington Hotel in Dublin at 8 p.m. on Monday, January 15th; you can visit his website at www.jodonohue.com