Without Phil we had no car. Nigel unhesitatingly called up his son Tony in Edinburgh and, sure enough, early next morning he was screeching to a halt outside Phil's in yet another vehicule from Nigel's seemingly endless collection of fabulousy clapped-out bangers. This particular model had at some stage in its history been a Volkswagen Passat, but now had more in common with something left over from a demolition derby. The rear seats had been removed to accomodate a sort of mobile kennel for Ben and Tilly - Nigel's black labrador and Tony's fox terrier (sort of). Nigel and I piled joyously into this chaos, together with the day's special guest star, Bothy, Phil's sister's young border collie. Phil laconically warned us of the need to keep him on a lead near sheep. So off we set in a state of wheeled insanity, heading out of Callander up along the Keltie Water through clinging mist and the wooded Brackland Glen. We parked near Braeleny farm. Although we were still in mist, we could sense the sun behind it and set off optimistically towards Stùc a 'Chroin, our objective for the day. I had Bothy on the lead, or rather he me. Utterly indifferent to my vain attempts at dressage, he effectively pulled me along behind him. Border collies are notoriously inexhaustible, but this particular dog, like some child high on E-numbers, was maniacally hyper-active and hopelessly attention-deficient. By heaving violently on the lead and ordering "heel" in what I supposed to be a masterful tone, I could get him to walk beside me for about a second, max. It was going to be a long day.

Continuing up the track, we met with our first obstacle. The bridge marked on the map as crossing the main burn at the point where the Allt Breac-nic flows into it was non-existent, swept away in some previous spate no doubt. There was nothing else for it. We would have to strike overland and follow the tributary upstream until we could find a fording point. Not wishing to be dragged nose-first through the bog and seeing no sheep in the immediate vicinity, I let Bothy off his lead. It was like firing the bolt from a cross-bow. He shot off and disappeared wildly over the edge of the steep bluff leading down to the burn. I was distinctly worried. Admittedly he was only a dog, but I did not relish the prospect of explaining to Phil, or still worse, his sister, that I'd somehow managed to lose their favourite pet. As it was, although still in view, he was right out in the middle of the deepest and fastest-flowing part of the Keltie Water, emitting the most unearthly howling yelp. Clearly out of his depth and being swept along in the eddying brown water, it looked as though he might be in serious difficulty. I called him desperately, my voice betraying anxiety despite attempts at an authoritative tone. I needn't have bothered. Next thing, he was scrambling over the stones, shaking the water off his coat and racing about in a madcap play-chase with Ben and Tilly. We found a spot where we could boulder-hop across the burn and continued on up to the reservoir formed by the damming of the Allt a' Chroin. The scene at the dam was a veritable Scottish Shangri-La. We were now basking in morning sunshine, with only shreds of residual mist punctuating the mountain idyll. All about us was the Gleann a' Chroin cirque: to the north Stùc a' Chroin itself, Meall Odhar to the east, with Beinn Each and Beinn Bhreac to the west and south-west. We lingered for a while before relunctantly moving on to tackling the real work of the day.

We climbed up from the reservoir to the croft at Arivurichardich. Looking back down, we spotted a movement in the glassy surface of the water, which we fancied might be the ducking and resurfacing of an otter. From there, the path led us diagonally up the hillside, then up a steepish section to Tiol nan Tarbh, where we sat down to enjoy a first instalment of lunch. Although the climbing had been hot work, the February air cooled us quickly and we were not too proud to don fleeces and anoraks. Continuing on our way, we wandered up the easy-angled Aonach Gaineamhach to the steeper final slopes before the summit of Stùc a' Chroin. At the cairn I interrupted the meditations of a lone climber who had reached the top a bit before us. We got to talking. He was a plumber and heating engineer from Glasgow who had the freedom to organize his work in a way that enabled him to get to the hills away from the weekends. We looked north-east across to Ben Vorlich. "On a Sunday they'd be like wasps over there!" He pronounced the word with a proper open 'a', which somehow conveyed far greater contempt than the tame, bloodless 'wosp'! Nigel and Tony joined us at the summit. Gazing to the south, we surveyed the entirety of the Lowlands of Scotland covered in cloud. A classic temperature inversion meant that we were lifted like demi-gods into a magical sunlit realm far above the dreary, workaday world and its grey fog-bound cares. We felt exultant, exalted, privileged to be able to experience a moment of rare wonder soaring above the ordinary plane of quotidian hebetude.

Sheltering from the wind on the northern slopes, we had another sandwich and contemplated the hills spread out before us. Ben More and Stobinian were prominent and Ben Nevis just visible in the distance. We had toyed with the idea of making our way down the rocky northeast ridge to the Bealach an Dubh Choirein and on to Ben Vorlich. But the way home would have involved negotiating some fairly intimidating peat-hags. So we turned to the west with the intention of making the complete round of the hills above Gleann a' Chroin. So far we had been engaged in classic guide-book stuff. Now we were headed off into the intoxicating domain of pointless mountaineering. No Munros and, despite Nigel's contrived calculations, probably no Corbetts either. Climbing, in other words, which had no purpose outside itself. Clambering over otherwise neglected lumps for no reason other than the sheer hell of it! Up and down, through and around heathery banks and rocky outcrops, the dogs racing about us and ahead of us, squabbling and playing. Up and down, up and down - Creag Chroisg, Bealach Glas, Bealach nan Cabar, a steep pull onto Beinn Each, down again to the Bealach Coire nan Saighead, then finally along the long, open ridge to Sgiath a' Dobhrain. In failing light we headed steeply down to the Breac-nic burn. As day turned into night, Nigel interrupted our downward plunge: "Listen, you can hear the silence." There was a sound of a distant waterfall, but it served only to emphasize the profound hush of the world drawing breath. We skipped across the burn and opted to head straight across the moss to the road. Because of the presence of sheep I had Bothy back on a lead, fortunately by now a choker lead which Tony had somehow conjured up out of nowhere. However, this proved to be only a partial restraint and I was very nearly dragged into streams and bogs which the dog cleared effortlessly, leaving me trailing awkwardly behind. Finally we made it to terra firma and marched on down the long track, our way lit by the moon and the stars.

What is happiness? Perhaps best not to inquire too insistently for fear of frightening it away, but it surely has something to do with that sense of the abundance of life, within and without, which we experienced that day climbing Stuc a' Chroin.