Although approaching his 75th birthday, sculptor John Behan has the round, cherubic face of a man far younger. More than just youthful, he looks innocent, as if his path through life has carefully, deliberately, skirted anything that might tamper with the purity of his seeing. "I go back over and over again. I'm the kind of sculptor [that] the themes come back again and again," he tells me, over tea in the Shelbourne Hotel, in the run up to his exhibition at the Solomon Gallery. "Maybe over 10 years. There are images I come back to again and again. Even one idea can take that amount of time." And so, in his work, we get the images, myths, legends and history that are the Irish identity – bulls, famine ships, Cuchaillain figures. The style of expression changes, but the fundamental themes are consistent. As he says, quoting Joyce, "life and art go in cycles."

Right now, the cycle of Behan's life is a sad one; his usually clear blue eyes are clouded by pain. Just before Christmas, his partner, Dr Emer MacHale, died from lung cancer. They met, years ago, at a party; "After that we just got together. It was as simple as that. It wasn't at all complex," he says. The house where they lived together, in the middle of Galway, John now inhabits alone. "It's terrible," he says, without attempting to hide the truth of this. "Just terrible. I often wake in the middle of the night, and realise, she's not here, she's gone. That's the worst bit. This time last year, we were planning to go down to the South of France. We knew Emer was not well, but after October of last year, she just went" – he makes a sharp-declining motion with his hand – "and she died on the 18th of December, just a week before Christmas."

Grief so often closes people over, restricts their sight, narrows their focus. Not so with Behan, who remains completely open and alive to the world. It seems that long habits of attentiveness and instinctive sympathy do not desert, even in a dark hour of need. "The really bad part of it is, it's not the lost years of you yourself, it's the loss for your partner. Her life is gone. She will no longer be there. And it's their loss – people say, 'it's your loss,' but I don't see it that way. I see it as her loss. It's a huge blow."

We talk about Caitlin Thomas, wife of Dylan, and the book she wrote after his death, Leftover Life to Kill. It is, we agree, a chilling title. "To lose your life partner is unbelievable," says John. "You don't shake off that kind of deep, emotional attachment that's been broken." And he is extraordinarily honest about the lack of comfort in the knowledge that this is common human experience; "It's happened to other people before now ... although there's no consolation in that."

There are, however, other sources of comfort. In the most natural way – nothing glib or forced – Behan is inclined to look for whatever positives there are. "I have really close friends," he says. "And the consolation was that in the last three years, there were two little grandsons born. That's really nice, for me. There's a famous essay by Ralph Waldo Emerson that says there are always compensations, no matter what. You have to see the consolations. If you go into a state of morbidity and collapse, you'll probably never get over it." And, because he is who he is, there is work. "If I hadn't got work, I'd go mad. I think I would anyway. I get up as near to 7am as I can, every morning. I just keep going. If I didn't do that, I don't know what would happen to me. I get up and I work every day, that's my rule, to myself. I work to honour the memory of Emer." Recently, he completed a garden sculpture, which attracts birds to it every day. "That's a memorial to her," he explains, "and I'm doing a thing for the hospital where she worked, of birds again. In relationship to her, I think of birds," he adds, simply. "I've come through it ok, but you know ... you can't forget it."

"I've plenty to do. It's a strange thing, I'm making a good living at the work I'm doing now, that's going well, but it's pretty hard to be thinking about the other aspect of life." So does now, on the eve of his 75th birthday, seem like a good time to look back, to reflect on his remarkable life so far? "I don't do too much looking back," he says. "I try to look forward, not back. The past is a different country, they say. You can get lost in the wrong aspects of nostalgia. If you are a creative artist, you want to be doing something new. As Ezra Pound says, make it new all the time. Even if it's an old theme."

He is adamant that old and new can exist together, that an image from ancient Ireland – the Morrigan, say, depicted by Behan as a scrawny crow – can say plenty about the contemporary world; "for an artist, anything that's made now is contemporary. You could write a novel about Hadrian in Roman times, and make it modern." And indeed, Arrival, his seven-metre long bronze sculpture of a famine ship that stands outside the UN headquarters in New York, is every bit as much a poignant reference to the tragic displacement of Syria's desperate refugees, for example, as it is a tribute to the starving Irish of the 1840s. It is the physical manifestation of the heartbreaking image Auden created in The Shield of Achilles; "they were small/And could not hope for help and no help came".

And if others don't get that fact, he is easy with that. "People may not be at all interested, but that's not my problem," he says, quite cheerfully. "My problem is to deal with what people feel; not with textual analysis or cold philosophical precepts or concepts, of what art is about. My role is to create and to help people to survive in hard times, and to provide hope. That's why my work is figurative mainly, I want to create a hopeful environment around the work I do."