In an elegant old Moorish house near the seafront in Lisbon there hangs one of the most striking photographs of an author I have ever seen.

It is of Jose Saramago, Portugal's Nobel Prize-winning novelist. Dominating one wall, this huge portrait is composed more of shadow than light. A gaunt Saramago, who is standing beneath the beams of an attic, stares grimly at the viewer. Around his waist is strapped a belt of books, with a dangling detonation wire, as if he were a suicide bomber. As the photographer Helena Goncalves and Saramago both knew, however, books can be far more explosive than semtex.

The image is appropriate because Saramago was in many ways a revolutionary figure. A militant Communist and atheist, he quit Portugal for Lanzarote in 1998 when the president removed The Gospel According To Jesus Christ from the shortlist of a major literary prize, because he said it was religiously offensive.

A charismatic, outspoken man who bore an uncanny resemblance to American comic actor Larry David, Saramago was not only a literary star but also someone whose political and spiritual views, as found in his experimental and often allegorical novels, won him a following that was almost devotional. On his death in 2010, readers gathered on the runway beside the plane that was to fly his body back to Portugal for burial, waving his books in the air as a final salute. At his funeral, Portuguese acolytes did the same.

But it did not end there. The house in which this photo hangs, Casa dos Bicos, is home to the Jose Saramago Institute. Originally built in 1523, this airy edifice has been renovated to hold the novelist's books, manuscripts, videos, portraits, newspaper articles, diaries and other memorabilia, as well as a research library of his work and a bookshop. Astonishingly, it was created without a single euro of state money. On Saramago's death, admirers simply made donations in order to honour him as fully as they felt he deserved.

As a result, the institute is not a mausoleum, waxwork or time-capsule, but a place in which it is hoped the spirit of his humanitarian beliefs can be promoted with talks, readings and discussions, thereby furthering his challengingly compassionate view of the world. A former car mechanic and journalist whose name means wild radish, which was his father's nickname and was accidentally inserted on his birth certificate, he once said, "I think it's time we writers went out into the world again and occupied the place we once held and which is now filled by the radio, the press and by television. We must encourage humanitarianism and spread the knowledge that thousands and thousands of people are still living in abject poverty."

Born in 1922 into a very poor background in a village near Lisbon, where his family later moved, Saramago drew on the rich but hard lives of his own kind as inspiration for his often fantastical, densely written work. A passionate advocate of the underdog, and an ardent non-believer in a loving God, his credo was that "our main task is to make ourselves more human".

One can see why his ideas touched so many. Even as a tourist with no word of Portuguese, who has read only one of his novels, I was moved by what the institute told me about him. And by the fact that outside its door an olive tree grows, beneath which his ashes are buried. This recalls an incident that deeply moved him as a boy. When his grandfather, who'd had a stroke, was told he'd have to leave home for treatment, he went around each of the trees in his garden and hugged them, knowing he'd never see them again.

Meanwhile, here in Scotland, which has not suffered the same economic devastation as Portugal of late, nor was ever as poor as this similarly small and proud country, we are still waiting for tributes worthy of our greatest authors, be they Robert Louis Stevenson, Hugh MacDiarmid or the many others who, like Saramago, have shaped our imaginations and even, in some cases, our lives.