Howard Jacobson: My quest for a coat, destination unknown

It's become compulsive now. I'm giving everyone the once-over. If I see a coat I like approaching, I move in close

Saul Bellow wrote somewhere that it is all very well for a writer to describe a character's thoughts, but if you don't also describe what the character is wearing when he has those thoughts, you haven't got to the heart of him.

So while I have urgent things to say about no-fly zones, pensions, Arab dictators funding British universities, etc, I would not be true to my novelist's calling if I didn't tell you what I am wearing or, more to the point, what I am thinking about wearing, while these subjects swirl about my head.

I leave shortly for a book tour of America that will necessitate my getting on and off about a dozen planes in about a dozen days, and need something I am not prepared to call a parka to travel in. As a rule, I favour long, flowing, black overcoats which give me, I like to think, the look of a stoic philosopher who could in other circumstances have been a rabbi. Spinoza, say. But such a coat is cumbersome for flying in. By the time you have taken it off and put it on again as you pass through security, and then struggled to find a locker with enough space for it on the plane, and then hauled it up and hauled it down again, you are exhausted. So something light, but also – because spring is slow coming to New York – warm. Light and yet warm, I say to shop assistants who make the mistake of asking if they can help me. No one can help me.

Of the 100 I look at, 30 are quilted – I trust I don't have to explain why I wouldn't be seen dead in anything quilted (even my coffin won't be quilted) – 30 are too long and make me look like Colonel Gaddafi, and 40 are too short and make me look like Ant and Dec. "It isn't the parka that's short," one assistant explains, alienating me at once since I'm not looking for a parka. "It's your jacket that's too's long." She offers me a shorter jacket to try on underneath. I refuse. I abhor short jackets. A man in a short jacket will never look serious unless he is a ballet dancer or a bull fighter, and even then it's touch and go.

When I do find one that's the right length, as light as I would like it and as warm as I must have it, unquilted and unhooded and with pockets adequate to what I know I will be carrying as I zigzag across America, but then again not too obtrusive – too many pockets and you could be mistaken for an amateur photographer or fisherman – I hit the biggest no-no of all. Words. What is it in the nature of casual clothing that makes their manufacturers suppose we will be willing billboards of their merchandise? If it demeans us to be walking logos in our business suits, it demeans us no less when we're wearing parkas, except I don't want a parka. Spinoza would not have worn a quilted track suit saying Tommy Hilfiger. I rest my case.

I fall to wondering what Shami Chakrabarti, director of Liberty, member of the LSE's ruling council, and the most self-righteous person in Britain, wears when she's off duty. She is on my mind because of the LSE's shonky connection with the Libyan dictator's family. I picture her in a parka with the word Gaddafi embroidered on it. I try not to be too censorious. We're all beholden to somebody we shouldn't be. Look at the people queuing all day to buy an Abercrombie and Fitch T-shirt. Abercrombie and Fitch aren't up there with Gaddafi, but the principle remains the same – we are created in God's image and shouldn't allow anyone else to mark us with their brand.

"You could always unpick the stitching," a lady in Fenwicks suggests, when I find the very thing I'm looking for, but with Barbour International sewn on to the top pocket. "Won't it leave holes?" I ask. She can't lie to me. "Probably." I see her wondering if she could get away with suggesting that the holes would give much needed aeration, but I am gone by then, lucklessly navigating New Bond Street, and then off to Regent Street where I intend to try Banana Republic, a shop whose shirts I get on with. But there's some witless would-be wisdom written on Banana Republic's window – "Life's a journey – explore it in style" – and I won't go in.

Everything is now a metaphorical journey. I made a documentary about the Book of Genesis recently, in the course of which they tried to get me to say I was on a journey. "I'm not," I said. They got their own back in the end when the programme won a prize and the judges congratulated me on my journey.

Meanwhile, my actual journey gets closer and I have no coat for it. I am starting to scrutinise what people are wearing in the street. I remind myself of William Blake. "I wander through each chartered street,/ Near where the chartered Thames does flow" – only Blake was marking marks of weakness, marks of woe, and I'm only marking what I refuse to call a parka. And suddenly the whole world seems to be wearing one. It's become compulsive now. I'm giving every one the once-over. If I see a coat I like approaching I move in close to check if it's logo-free. People are regarding me strangely. Why am I staring at their chests?

I recall an old girlfriend telling me that she once caught herself looking at men's trousers in the streets and, having become aware of it, found it impossible to stop. "They think I'm looking at their penises," she said. "So what are you looking at?" I asked her. "Their penises," she told me.

Her point was that once you know there's somewhere you mustn't rest your eye, you can't rest it anywhere else. Shami Chakrabarti must have felt the very opposite about human rights abuses in Libya.

And so it is with me. I have become not-a-parka-fixated. And I'm not just looking now, I'm grabbing surreptitious feels, trying to gauge the quality and weight of the material. If this goes on, I will be arrested. And it won't help in the slightest to explain that, no matter how it appears, I am in actuality on a journey of the mind, thinking about no-fly zones, pensions, Shami Chakrabarti, and the strange truth that the most sanctimonious among us are always those with the least reason to be.