When I was at school, I was taught that what differentiated man from the rest of creation was that man alone used language and tools.
That's no longer credible, as biologists have shown over and over again that many species of animals communicate and use tools.
So what now differentiates man from brute creation? Let me suggest one way. Only man cooks. It's Homo sapiens' unique difference, setting us apart from all other creatures.
Cooking started with the discovery of fire, when fresh meat was roasted by our ancestors. Since then, techniques and skills have evolved, and gradually we learnt that good food was a pleasure to be enjoyed.
But great cuisines need several things in order to evolve.
First, there has to be abundant raw food, then there has to be a society sufficiently advanced that it can sustain people who specialise in cooking, and, last, there has to be someone rich enough to pay them.
When all these things are in place, then serious cuisine comes into being, replacing the more basic and primitive eating for survival.
Great civilisations have produced great food. In many ways, having an advanced cuisine is a signifier of civilisation, as many an epicure has pointed out.
Mostly, these great cuisines have started in the courts of kings and gradually those skills made their way down the social ladder.
There are exceptions, of course. Most of Italian regional cookery comes not from royal courts but from the peasantry, who evolved fairly sophisticated techniques for dealing with their own raw produce.
There's little doubt that Japanese cookery falls into the former category, coming to us from the court of the emperors.
There's a finesse and delicacy in Japanese cuisine that puts it far away from the peasantry.
Indeed, should you wish to become a sushi chef in Japan, you need to train for seven years, such is the complexity of that art.
Although Dublin is well served with most of the world's cuisines, Japanese outlets are not exactly thick on the ground.
I hadn't been aware of a Japanese restaurant in Ballsbridge until I did a little research on the interweb.
It's possible that I hadn't noticed Koishi when I drove through Ballsbridge because it's on the first floor, specifically opposite the American Embassy, above Chandni, the Indian restaurant.
I arrived with Marian Kenny on a mid-week night and we got a table by a window, Marian looking into the restaurant and me with a view right up Herbert Park Road, as far as the Dublin Mountains.
The interior is lightly themed; a few paintings, three Samurai swords and some Japanese ideograms painted on pillars.
We got two menus -- a large one on shiny card and a smaller one which listed all the sushi and sashimi elements and combinations.
As well as those, there was a small blackboard with the day's specials, so the choice of dishes was large.
With so many choices it took us a while to order, but eventually we did and ordered drinks -- mineral water to share and a beer for me.
Since we were in a Japanese restaurant, I felt I should order a Japanese beer, the dry Asahi.
Our starters arrived, the gyoza for Marian and the tuna and salmon sashimi for me.
Marian has to stay away from shellfish, so much of the menu was unavailable to her, but the gyoza was perfect, as it was chicken and vegetables in small dumplings which were fried.
I really liked the taste of them; I thought they were subtly flavoured and worked well.
As for me, I was happy with my choice. I'm completely converted now to the idea that raw tuna is preferable to cooked. I got Marian to try a piece and she liked it, so there's another convert.
The salmon sashimi was also good, but tuna is definitely the best fish for this way of presenting it.
After a lot of discussion we'd settled on these main courses: stir-fried beef with ginger and vegetables for Marian and the deep-fried breaded pork for me.
When the dishes arrived, Marian looked forlornly at her beef, saying, "It's too brown, I can't eat this".
Gallantly, I instantly swapped with her, giving her my pork. After she'd tried it, she found it too rich.
Immediately our host was at the table. "Is there a problem?" At first Marian said no, but he persisted: "You have to eat, if this doesn't please you, there are plenty of other dishes on the menu."
Then he suggested she might like to try meatballs and chicken on a skewer, which she did. That dish suited her well and I enjoyed the beef dish, nearly finishing it.
As we ate, Marian asked me, "Are you going to call me Marian Kenny in the review?" I said I always had done in the past.
Then she said: "Why can't you call me the blonde, the way AA Gill does in his reviews? Marian Kenny sounds very formal."
Okay, from now on it's 'the blonde'.
There was just enough room for a dessert, so we looked at the menu. It reinforced my belief that Japanese cuisine, like many Asian cuisines, is not big on desserts.
Our choices were tiramisu, cheesecake, ice cream, fresh fruit or tempura ice cream. That last one caught my attention as it was the only one that didn't appear to be European, so we ordered it to share.
When it came, it was a large ball of ice cream with a crispy coating. Nice enough, but nothing special.
I finished with a decent espresso, which brought our bill to €79.
I suspect that to enjoy Koishi at its best, you should choose as much as possible from the extensive sushi and sashimi menu.
These dishes really seem to be the strong suit of the kitchen.
Tel: 01-668 8393
On a budget
A good budget buy is from the lunch menu, where there are a lot of bento boxes listed. These are a complete meal on a tray with various sections, and they’re also available as a takeaway. They range in price from ¤13.40 to ¤14.50.
On a blowout
There are set options on the sushi and sashimi menu, which would be perfect for sharing. For example the ‘matsu’, which gives you 28 pieces for ¤42.65.