It is raining at the taxi-rank opposite the Botanic Gardens. It is doubtless raining in many other places as well but this is the only one I'm interested in at the moment. I don't have a coat on and turning up my jacket collar is no substitute. I'm cold and wet and getting wetter. Everything seems dark, including my mood.

A taxi comes off Great Western Road and makes a u-turn into the rank. I climb in, discontinuing my mental tirade against all Glasgow taxi-drivers and reflecting more charitably on the number of times in my experience hackney cabs have justified their Glaswegian nickname of 'black ambulances'. I tell the driver my destination and we set off through grey rain, along grey streets, under a grey sky. The driver studies me in the rearview mirror with the eyes of a man who has never lost his curiosity about things.

'Have ye ever wondered,' he says, his eyes still flicking on to me more frequently than seems consistent with maximum concentration on his driving. 'Have ye ever wondered whit would win in a fight between a crocodile and a shark?'

I am, as they say, nonplussed. In all my deep ponderinp on the world and its many manifestations, this is one I've missed. It seems such a natural, even inevitable question the way the taxi-driver says it, I can't imagine why I've never asked it myself. Shamefacedly, I acknowledge how unthinking my progress through life has so far been.

`It's an amazin' thing,' he says. `Ah'm sittin' in the hoose the other night readin' a book. An' Ah shouts to the wife, "Hey, hen. See the way Ah'rn always sayin', `Ah wonder what would win between a crocodile an' n shark?" (I have an eerie flash of the kind of conversations that must take place in his house: `See's ower the paper, hen. Bet ye there's nothin' in it aboot crocodiles an' sharks the day again.') "Well here's the answer here."'

I sit tensed in the back of the cab, no longer a mere traveller to an address but a journeyer into esoteric knowledge. But the taxi-driver, like all true gurus, knows the path to wisdom is a winding one.

`Seems there's this river in Australia. Right? An' at the mouth of it ye'vc got 'yer crocodiles. An' then yer sharks are swimmin' in. Into the estuary, like. Fair enough. Wallop. A square go.'

He seems to need for the first time to concentrate totally on a tricky piece of steering. He knows he has me. I try to ask him nonchalantly, to make sure my voice isn't quavering with suppressed emotion.

`So what would win?'

He glances at me in the mirror, looks at the road.

`Ah suppose it's obvious when ye think about it,' he says. 'The crocodile. Seems it bides its time, one bite, holds on, ta ta shark.'

So there we are, another nibble at the infinite apple of knowledge. Brooding in my back seat, I decide daringly — for David Attenborough I'm not and what do I know about crocodiles and sharks? — that I don't believe him. Isn't it true, my scepticism is whispering like a wee boy in the back row of the class, that crocodiles are freshwater creatures?

But I am very glad he told me. He has, as the poet says, saved some part of a day I had rued. We've been exploring together to other climes, he and I, however briefly. The rain receded just then and it was like the moment when Dorothy leaves the black and white farm and walks into the technicolour of her search for Oz.

The memory of such experiences brings me nearer to the essence of my sense of Glasgow. No matter what harsh anomalies I find in the city, no matter what misgivings I may have about what's happening to it, no matter what changes overtake and alter what I thought was final, a moment like that is a familiar landmark and I recognise the place again.

I stood once at the bar of the Gowdoc in Great Western Road, feeling like a tortoise that had just been de-shelled. I no longer remember what troubles I had then but I had decided they were big ones. I was standing in for Atlas. Nobody knows the trouble I've seen. A small man at the bar beside me suddenly spoke.

`How's it gaun, big yin? Ye don't look that happy. You think you've got problems? Listen.'

It seemed that a few days ago he had met a friend he hadn't seen for years. They had gone on the skite together and the wee man hadn't been home for nights, three, I think it was. He was asking my advice. Should he go home tonight or, since he was bound to get laldy anyway, should he have another night at it?

Always at such times I know that this is Glasgow: land of the unsolicited confidentiality, country of the unasked for information, city where Greta Garbo wouldn't have been allowed to be alone— 'Who's the big wumman wi' the funny hat? Get ower here, ya big stoater, an' jine the comp'ny. Charlie, gie 'er a piña colada.'

(To read the next post in this series click here.)