THERE is a rainbow-filled cloud dancing on the treeless slopes of Harris as the CalMac ferry pulls towards Tarbert and I take this as a good omen. While some of the other islands are just a hop and a jump from the mainland, taking the boat to Harris and Lewis feels like travelling to the edge of the world.
Stopping for petrol in the garage in Tarbert, I immediately feel I have stepped backwards in time. There is a basket of eggs for sale on the counter and the windows are stocked with huge heather-coloured balls of wool, used for making the famous tweed.
In some ways, Lewis and Harris are one island, but they are always spoken of as two. It isn't the sea which divides them, but a huge stretch of dark moody mountains, which must have been almost impassible in winter.
As I cross towards Lewis I take in the strange treeless landscape, and spot neat stacks of peat, which are still used as fuel by most of the people here. Sheep stray on to a road which has the best surface of any I have travelled on the islands.
Lewis and Harris are known for their Christian orthodoxy, and the papers have been full of the controversy concerning the first Sunday ferry from North Uist to Harris. It is still considered rebellious to hang out washing on a Sunday, yet those in the know say change is in the air. Still, there are many who wish to preserve the peace of the Sabbath, saying it is an antidote to the ways of the modern world, where everything moves too fast.
Tonight I'm staying at Callanish, Lewis, and as I arrive the sky is aglow with pink and orange evening light.
Encouraged by my host, Neil Macarthur, I head straight up to the standing stones, famous around the world as a prehistoric temple of the moon. The fields are still boggy from days of rain and the stones are deserted when I arrive. It is astonishing to think this circle of megaliths has stood here for 4,000 years and is older than the Pyramids of Egypt.
It's wonderful too, to be able to walk up here in solitude, with nothing to keep you from the site but a little wooden gate.
It will be less peaceful in May and July, when thousands of new-age tourists are expected to witness the rare lunar standstill, which happens only once every 18 years.
With my head full of mysteries, I head for the Doune Braes Hotel for a meal which is both sumptuous and unexpectedly bizarre.
The chef, Jeyan, who is from Sri Lanka but describes his nationality as "global", dances around the tables, offering to feed us anything we choose, whether it is on the menu or not. We ask for a seafood platter and are rewarded with a dish containing half a lobster, some huge blue crab claws, scallops, cod and a pile of breaded garlic mussels. It is enough to feed a family of seven.
Afterwards the chef, who came to Lewis via Finland, hands us his calling card which proclaims: "Me and my f2 cooking don't have any cross-contamination with religions, nations, traditions, complications of food chemicals!!!"
Fortified with fish, I realise there are still a few streaks of light in the vast northern sky and travel up the road to take a look at Dun Carloway broch.
It, too, is deserted and I can scramble free through the half-buried entrance of this stone age stronghouse, 2,000 years old but with rooms and staircases intact.
Back at my B&B, Loch Roag, I settle down for the night to think about how close the distant past seems here on Lewis - and through a skylight in my attic bedroom I see a falling star.
Next day, I am a little weary from my travels and the genius waitress suggests I try a drop of Drambuie with my porridge. I find a precedent for this habit in the account of Dr Johnson, who wrote of the universal Highland habit of taking a nip before breakfast: "No man is so abstemious as to refuse the morning dram, which they call a skalk."
With a fresh sparkle in my eye I set off to explore the north of Lewis, where the fields are full of monoliths and the old black houses still stand alongside the white houses which replaced them. Nothing, it seems, ever falls down here.
At Gearrannan Blackhouse Village, I am welcomed by Mairi MacRitchie, who speaks with the slow Gaelic lyricism of many from this island of storytellers. Like many islanders, she spoke only Gaelic as a child, of the particular Lewis variety which is rich with Norse words and pronunciation.
The last black house to be lived in at Gearrannan was left by its elderly inhabitants in 1974. The house is still much as it was after being modernised in the 1930s, with a range, wood panelling and a chimney, but the animals are still penned in the end of the house and the floor slopes sharply down the steep stony face of the cliff.
"This is my heritage and I'm proud of it. I have nothing but admiration for these people, they were hard-working people and they were very neighbourly," MacRitchie says.
She tells me the story of the Iolaire, which sank in Stornoway Harbour on 1 January, 1919. More than 200 men, most of them soldiers returning from the First World War, were drowned on that day.
"The older I get, the more sad it makes me to think of it," she tells me.
I leave the ghosts of Gearranan and travel up the plain to the Butt of Lewis. As the man at the Arnol Blackhouse Museum tells me: "You cannot come to Lewis without going to the Butt." The modern world is encroaching; as I cross the plain, I notice scores of yellow posters saying: "No wind factory here."
The sky is brilliantly blue as we reach the Butt of Lewis lighthouse and peer over the steep cliffs to look at the dark turquoise sea, which is throwing up great sprays of white.
It's a long drive back over the hills to Harris, where I will spend the last night of my island odyssey. But I can't resist the chance to take a detour along the beautifully named Golden Road.
Donald MacLeod, The Scotsman's chief photographer, has called this "the land of passing places" because every turn in the road takes you to another tiny shining rock, a white painted house or a ruined cottage. Others have likened the treeless gneiss landscape to the surface of the moon.
I fancy another fish feeding-frenzy, so I head for Rodel Hotel, which advertises widely. Sadly, last night's experience is not repeated. Service at the Rodel is not so much relaxed as comatose, and while the scallops and langoustines are fresh and sweet, the potatoes taste like yesterday's scraps, reheated in the microwave.
I wish I'd booked ahead and eaten instead at Scarister House, an elegant Georgian farmhouse which is one of the island's most famous hotels.
But I'm glad I visited Rodel, to see the Church of St Clement, 400 years old and full of stunning stone carvings of sleeping medieval knights.
On the same road is a genealogy centre, Seallam! - pronounced "sha lum" - where researchers Bill and Chris Lawson have collected a huge resource of parish records and emigration documents, for people who have come to the islands to trace their ancestors.
Up on the hill are a cluster of beautifully designed modern holiday homes with roofs made of bright green turf. A couple sit outside one of the houses, drinking tea and taking in the view, which stretches, over vast sandy beaches, to the Castaway 2000 island, Taransay.
As she makes breakfast the next day, Catherine Morrison of Beul na Mara asks me about my island tour, and says that while she worked for years in Glasgow as a physiotherapist, she always knew she would come back here to the shore where the white sands stretch for miles.
After a long drive across the island, I suddenly notice an unusual aromatic scent in the air, which I realise is the smell of trees.
I arrive in Stornaway. After my journey into the past, it seems a bustling metropolis, and I realise with a sigh that it is time to bid farewell to island life.
Lewis and Harris: The facts
• HOW TO GET THERE: Caledonian MacBrayne run services from Uig on Skye to Tarbert on Harris and from Ullapool to Stornoway on Lewis, www.calmac.co.uk
Loganair runs regular flights for BA to Stornoway from Glasgow, Inverness.
• POPULATION: 19,918 (Lewis and Harris combined population)
• MUST SEE: The Golden Road, which begins on the A859 south of Tarbert, winds through a spectacular landscape of gneiss rocks dotted with hidden lochs, white cottages and ruined blackhouses covered with flowers. The romantic-sounding name is actually a sarcastic commentary on the huge cost of building the road.
• FAMOUS ISLANDERS: Sir Alexander Mackenzie, the explorer who was the first European to cross Canada, was born in Stornoway in 1764. He named the river which led to the Arctic Ocean as Disappointment River, because it didn't lead to Alaska as he anticipated, but it was later named Mackenzie river in his honour. JM Barrie, creator of Peter Pan, wrote the drama Mary Rose while staying at Amhuinnsuidhe Castle in North Harris, while the all-American cowboy movie star John Wayne, left (real name Marion Michael Morrison) claimed kinship with the Morrisons of Lewis, and the mother of the American billionaire Donald Trump hailed from Lewis.
Industrialist Lord Leverhulme bought Lewis in 1918 and promised to make it a land fit for heroes. However, the islanders resisted his ambitious plans, saying; "This honey-mouthed man would have us believe that black is white."
• STORIES AND LEGENDS: The Lewis chessmen, including the famous beserker who is biting his shield, were discovered at Uig in 1831 in a drystone chamber. Believed to have been made in Norway between 1150 and 1200, they are carved from whale teeth and walrus tusks. Some of the chessmen were originally stained red.
• WHERE TO STAY: Loch Roag B&B, Callanish, 01851 621357, www.lochroag.com
Beul na Mara, Seilebost, South Harris, 01859 550205, www.beulnamara.co.uk
Blue Reef Cottages, Scarista, www.stay-hebrides.com
You can stay at Gearrannan Blackhouse Village, www.gearrannan.com
• WHERE TO EAT: Waterside Restaurant, Doune Braes Hotel, Callanish, 01851 643252, www.dounebraes.co.uk
Scarista House, 01851 550238 www.scaristahouse.com
• USEFUL CONTACTS www.isle-of-lewis.com
Seallam! Visitor Centre, 01859 520258, www.seallam.com
Museum nan Eilean, Stornoway, 01851 709266
An Lanntair Arts Centre, Stornoway, 01851 709266
Island walks: Strone Ulladale
Distance/Time: Eight miles, allow four to five hours.
Where to park: Just off the B887, the western coast road by West Loch Tarbert, just over a mile west of Cliasmol, where the road crosses the River Eaval.
Refreshments: Plenty of choice in Tarbert.
The Walk: Many hillwalkers go to Harris to climb Clisham, a Corbett and, at 799m, the highest hill in the Outer Hebrides. Climbing it does not take a full day, as it is close to the A859, which links Tarbert on Harris, to Stornaway on Lewis, yet within that time, most walkers will be smitten by the delights of Harris and will plan to extend their stay into a week of exploration. In this rocky and enchanted island, there is so much to see and do, and it is not at all necessary to climb any other high tops. Some of the lowly glens are a delight in themselves. One of them, Gleann Chliostair, lies only some five miles west of Clisham. At the top of the glen the watershed overlooks Glen Ulladale, whose upper reach is guarded on the east by a hill modest in height, Strone Ulladale (Sron as mapped), but definitely not modest in appearance. It is one of those must-visit places.
So what is so special about Strone Ulladale? Some would claim it to be the most impressive piece of rock in Britain, an overhanging cliff of hard, polished gneiss, apparently in the act of falling into Loch Ulladale. And the bonus is that Gleann Chliostair gives access to view it, yet even if the weather turns adverse, the walk in the glen will still offer a satisfying and sheltered outing.
From the start at map ref 052078, just over a mile west of Cliasmol, a track leads for one mile past Loch Leosaid to a power station, but do not let that put you off. Continue on the track to the small dam at the end of Loch Chliostair, at which point the glen really closes in, and the track is replaced by an excellent path. The names of the hills on the east side of Gleann Chliostair - Cleiseval, Oreval and Ullaval - betray their Norse origin, -val being from the Norse for peak (from fjall).
The slabby slopes of Tirga Mor dominate the west side of the glen, with its craggy flank of Creag Chliostair overlooking the loch. The watershed is at the north end of Loch Ashavat at a height of 240m. Given the three miles to reach that point, the overall gradient is modest. The watershed, where there is a small bothy, makes a good turning point. For more impressive views of Strone Ulladale, descend one mile by the Ulladale River to Loch Ulladale, a drop of 170m. Continuing by the south shore of the loch, then north-east towards Mullach na Reidheachd, gives a good viewpoint.
Map reference: OS map 14, Tarbert & Loch Seaforth, grid ref 052078.