I should give you fair warning: I am going to talk about china patterns. Really, if all you can think of is the French election and what is happening in Greece, I advise you to look away now.

A new thing I have discovered is that when I am having a complicated or unsettled day, I soothe myself by shopping for vintage china on Ebay. I have developed an urgent passion for delightful old plates. I like the crazing on them, the faint wearing of the pattern; new plates suddenly look flamboyant and vulgar. The searching is not just random browsing, but quite discrete and acutely focussed. I like, I discover, things from about 1870 to 1940. I do not want pointless articles such as trios (a tea cup with saucer and side plate), which are very popular. I want proper utilitarian soup bowls, pudding plates and dining plates. I may stretch as far as a platter or a tureen if I am in whimsical mood.

None of this is of any intrinsic interest. Middle-aged woman has Ebay habit, big whoop. But I am always riveted by those activities which make you reconsider small, taken for granted things. The china habit has been making me think about the mysteries of taste. Everyone agrees that taste is subjective, and probably comes from cultural influences. I could not tell you how exactly it is formed, or when, or why it may suddenly change, or which part of the brain it is connected with, or why it dies so hard. I find it fascinating that it may be at its most dogmatic around the most minute and completely trivial matters. (I hear the voice of my younger revolutionary self: how can you ponder china patterns when the world is so oppressed?)

To my surprise, I have discovered that I absolutely abhor a plate with a frilled edge. I’m not sure if this is the correct nomenclature, being no china expert, but what I mean is when the rim of the plate has vertical ridges all round it. This turns out to be a quite commonly found style, so many people must love it. Not only do I not like it, but I would be actively sad if I had a plate like that in my possession.

How can this be? No one took me aside in my youth, and said: ‘Whatever you do in life, never, ever, have a frilled edge on your plate.’ It was so not spoken of that I do not even know the correct descriptive term. Yet when my eye falls on such a thing, it recoils in horror. I also discover that I only like perfectly round plates, not the ones with slightly waved edges. I utterly reject any representation of fruit. Again, I have no idea why. I like fruit, I eat fruit, fruit can be an aesthetically pleasing thing. But not painted on a plate; not under any circumstances.

I like anything with blue or green on it; I do not like silver or red. I am a tremendous admirer of items in the Chinese or Indian style, however madly patterned; busyness in any other style is at once cast aside. I love Art Deco in Noel Coward sets; I do not, it turns out, enjoy it in a dinner service.

Where on earth were these decisive prejudices learnt? I vaguely remember one of my grandmothers having pretty china; I have no memory of what we ate off at home. My mother never sat me down and read me a lecture on what was and was not acceptable in matters of porcelain; I remember no word on the subject. It is as if all these violent likes and dislikes were randomly born in me, and endure as viscerally as if they were a matter of life and death. The pleasure I take in the old china is also insanely disproportionate. I recently hunted down a lovely set of plates and tureens from a maker called S Hancock. The glaze is a little foxed, as if they were beloved and well used; I should say they date from about 1910, and were probably in the possession of a prosperous and respectable middle-class household. They have a bright cobalt rim and a very delicate tracing of faded gilt just inside; the centres, which were once white, have dimmed to a lovely ivory. Every time I get them out, I feel a lurch of happiness.

None of this makes any difference to anything. I have no clue where it all springs from. I like to understand the mysteries of neuro-science. I suspect though, it would take more than an MRI machine to work out the odd vagaries of my china freak.