The Scottish writer, poet and musician remembers childhood holidays spent walking in the north-western hills of Scotland. "I have lots of associations with hillwalking and childhood," he says. "For family holidays we used to go up there. We grew up in Stirlingshire but my dad loved the west coast and for years we'd go there. To me, Ullapool and Lochinver are the best of my childhood."
The writer, who lives between Edinburgh and Orkney, has never lost that love. From climbing in Glen Coe to trekking up Mount Everest, he's experienced the extreme highs and lows – the dangers and the exhilarations of outdoor life. "It's about a passion that's about a life more intensely explored or lived," says Greig.
Hills, both mountainous and manageable, have featured in Greig's work. His most recent book, At the Loch of the Green Corrie, combines (among other themes) meditations on Assynt, in the north west of Scotland, and a three-day fishing quest. Much of his previous work, including the long poem Men On Ice, has also been inspired by or written about his climbing and hillwalking experiences.
Now Greig is presenting Dancing with Mountains, a programme for Radio Four on visual artists inspired by climbing, which is due to be broadcast next week. The documentary will feature his long-standing friend, Scottish artist Rob Fairley.
"When the director approached me about the idea of doing some kind of documentary about visual arts and climbing I immediately thought of Rob," he says. "When I met him I was struck by his paintings – they're not only of the Scottish and Himalayan mountains but they are informed by and made strange by the mental and emotional experience you have at altitude – the brain is starved of oxygen and it's an odd way of seeing and being."
A chance meeting with Scottish mountaineering legend Mal Duff, who died in 1997, introduced Greig to the world of intensive climbing expeditions: "I got into climbing by a happy accident. The first trip was in 1984, then we went onto the Tibet side of Mount Everest in 1985. It was only meant to be one trip, then it turned into a second, then it turned into a third in 1986."
The Himalayan trips inspired two books, Summit Fever and Kingdoms of Experience. "I carried on doing Scottish winter climbing for a number of years [after the Himalayan climbs] because I loved the scene and I loved the people," says Greig. "Usually I was based either round Glen Coe or round Ben Nevis." Sometimes the Scottish climbs proved more challenging that those abroad. Greig says: "I found it often more frightening than the Himalayas. Scottish climbing is basically much steeper and I don't like the exposure – I don't like heights."
Greig, now 60, doesn't climb any more. Instead, when he can, he gets out onto the hills of Scotland. Those scrambling walks and gentle ascents provide him with both solace and inspiration for his work. "After two or three hours of being in the hills, you kind of go into a more clear but dreamy state," says Greig. "It does help to clear my mind. I go hillwalking when I can. I live very near the Pentland Hills in Edinburgh so I get onto them as often as I can. The hills feel like the earth or ground to me, but at the same time they lift me up – it's really hard to explain. It's about being in a higher position but it's also about being grounded in your physical body on the planet."
The less visited parts of the Pentland Hills and the slopes around Assynt are still among Greig's favourite places. "The mountainscape in Scotland that's most special to me is definitely Assynt. It sounds daft but they're the best shaped hills – what's striking about the hills in Assynt is that each one of them is actually quite different from the other. There's no shape repeated."
Greig also enjoys the physical challenge too. "When you're walking on the flat or sitting down you don't notice your body all the time – you don't notice that you're a physical being.
"It's quite hard work and I like that aspect of it – putting in a hour of sweat going up a hill to this special place, then yomping home with tired legs."
Dancing with Mountains will be broadcast on BBC Radio Four on Thursday September 6 at 11.30am