Let's have one other gaudy night," says Antony in Shakespeare's play. "Call to me all my sad captains; fill our bowls once more. Let's mock the midnight bell." And mock it we did on Saturday at my old Oxford college's Gaudy Night. These reunions occur every six or seven years, and give ageing graduates a chance to monitor each other's progress in the, ahem, corridors of power, to exchange fascinating views and to mock each other's absurd pretensions towards importance in the public eye.

Surveying the physical changes wrought by time is no longer as dismaying as it was some years ago. When you're 40, the sight of your one-time room-mate Philip, once a skinny ephebe with golden ringlets, now transmogrified into a burly renegade with a head like a Sumo bouncer and a body to match, is frightening. In your mid-50s, not so much. You just hope you won't have to endure too many conversations about prostate cancer.

Not much has changed about the 700-year-old college, except the bloke on the roof. This is one of Antony Gormley's mass-processed bronze figures that are posed dramatically on skylines across the nation: but the Man on Exeter College is a particularly disturbing specimen. "You can see it most clearly from the gate of Balliol," said the rector, Frances Cairncross, "but that can't be helped." The statue has, she noted, prompted anxious American tourists to shout: "Fer Gahd's sake, don't jump!"

One thing that's changed since the last gaudy is that old boys aren't constantly badgered to endow their college with large sums of money or remember it on their deathbeds and inscribe it in their wills. Instead, we're invited to think of ourselves as family – an extended family of like-minded intellects who might feel like helping junior family members with their education expenses.

But are we really a family of like-minded intellects? A theme of the evening was CP Snow's dictum about the Two Cultures of arts and science and how seldom they overlap, because of the reluctance of humanities students to grapple with anything harder than a three-pin plug. Readers of Ian McEwan's new novel, Solar, have included scientists impressed by his research, and long-term McEwan fans comprehensively at sea in his fictional world of climate-change research. Only last week, my colleague Tom Sutcliffe remarked how much more intellect was demanded to understand quantum theory than to understand Paradise Lost.

In the bar we talked about all these things, about medical breakthroughs, Hadron Colliders, stuff like that. I kept my end up. When David K, a physics undergraduate back in 1972, talked about his work in genome sequencing, isolating the roots of malaria in Africa, I nodded sagely and asked, you know, intelligent questions ("So this malaria gene – how big is it exactly?") and impressed my interlocutor with my grasp of human cell research. Then he started asking about the arts.

"Do you know this chap, Brian Sibley who writes about art in an evening paper?"

"You mean Brian Sewell? He's very highly regarded, very mocking and brilliant."

"He called Matisse 'overrated'. Is that true?" I was nonplussed. "It's neither true nor untrue," I said. "It's just an opinion about art."

"But if it's unverifiable as true or otherwise, why read this person?"

"Er, David ... " I said. "This is criticism. These are just pronouncements which ... "

"You review books don't you?" he persisted. "How does that work? You read the book to the end, then – what? – you find something to say about it? You offer a value judgement?"

"Well, er, yes," I said, "you infer the author's intention in writing it, and try to assess if he or she has pulled it off."

"What if you're wrong? How do you know you've understood the author's intention?"

"David," I said, "I don't think you've grasped the basic premise of literary criticism ... "

At which he smiled. It was only later, on retiring at 4am when the malt whisky ran out, that I realised. My former co-student had been letting me know something – this was how scientists would sound if they asked arty folks questions with the same ignorance that arty folks display when asking about science. A salutary lesson, silkenly delivered, by a brainier sibling in the graduate family.