If the relationship is more seasoned, there is quiet camaraderie in the decision to give it a rest.”
So this is not a suitable site for those of us fuelled by Viagra. Although Griscom and his contributors are forthright and graphic, sex is perceived as being “reliably trauma-inducing”, and a rarefied interplay between erotica and culture is the aim of the game.Griscom encourages his users to share their “shame and desire” in the “Threads and Roles” sections with established writers such as Thom Gunn and Robert Olen Butler and exhibitionists like Lisa Palac (“How Dirty Pictures Saved My Life”) and Marion Winik (“The Author Has a Candle in the Window, and A Fire Somewhere Else”), so the quality of the writing inevitably soars and plunges. But then a good website is nothing without its share of dross.In an essay specially commissioned for the Voice Box (which this week features a “virtual round-table discussion on the zoning of child sexuality in art, advertising and the American household”), Erica Jong wades in on the executive pound of flesh in an essay on Bill “Zeus King of the Gods” Clinton as the alpha male who refuses to be bound by bourgeois constraints. Among those discussing child sexuality are Naomi Wolf and Nancy Friday. The calibre of the contributors this site attracts is evidence of its high-minded, literary ambitions, and on the whole these ambitions are fulfilled.When it comes to images, though, Nerve o’er reaches itself. While there are nudes for every taste – “Passive-aggressive nudes”, “Moody nudes”, and “Avant-garde Male nudes” – Leslie Lyons with “Portraits of a Pale, Still Girl” aims to capture more than naked flesh.

Inspired by Egon Schiele’s stark-eyed, sharp-boned muses, she roamed the streets of New York in search of a Manhattanite reincarnation. Once she’d found her, the hapless girl agreed to recreate the poses depicted in Schiele’s 1910 series of explicit drawings. The original are posted alongside Lyons’s interpretations but whereas Schiele’s tortured gaze never rests on the obvious, Lyons’s seems stuck on round-eyed, thumb-sucking soft porn.Still, if that’s your bag, go and see for yourself. But do not forget to drop in on “Jack’s Naughty Bits”, a column that brings great sexy scenes from the history of literature on to your shimmering (breath-fogged?) screen. This week, James Joyce goes all the way while Lawrence Durrell barely gets to first base. I’m sure Mr Griscom would approve.’Nerve’ can be found at: www.nerve .

When botanists say that the rose is related to the thistle, are they reporting a discovery or making a decision? That is, are they telling us about the real nature of the world, or are they choosing to group certain things together because doing so is – to put it bluntly – useful?

If you think the former, you believe that things have an inner nature, which makes them what they are independently of our knowledge: on this view a rose and a thistle are essentially related. If you think the latter, you regard our taxonomies as the projection of our intellects: we class roses and thistles together because practical and theoretical convenience so invites.
These philosophical questions are freshly in the news. Scientists at Kew have recently turned botanical taxonomies upside down by taking DNA as the criterion for plant classification, in place of the system – originated by Linnaeus – which relies on appearances. Linnaeus’s system says that one of Buddhism’s holy plants, the lotus, is related to the water lily; DNA comparison says it is related to that familiar London inhabitant, the plane tree. Other such dramatic surprises abound in the new system.Using DNA as the criterion seems to square with the view that botanical taxonomies succeed in carving nature at its joints, quite independently of human needs and interests. But does it? There are some problems in the way of thinking so.The members of any collection can be grouped together in different ways, depending on the criteria chosen. One can for example classify books according to subject, or author, or title, or even colour or size.

Which classification you choose depends on your needs: are you arranging a library, or trying to store volumes in an oddly shaped space? Scientific classifications appear less arbitrary because of their relation to scientific laws: they can be tested by how well they function in theoretical and experimental ways. But even here questions of interest apply: you group plants together in one way if you wish to identify species poisonous to humans, and in a different way if you wish to identify plants resistant to given sorts of pest.The DNA test, however, seems to provide an objective yardstick which cuts across such classifications. Indeed it seems to give us the essence of botanical kinds, unmasking their inner nature. By the “essence” of something is meant that property which makes it what it is: if it lacked that property it would be either something else or nothing. Essential properties contrast with “accidental” properties, those that a thing might have or lack while still being itself. For example: it is an accidental property of a given potato that it is covered in mud or weighs a pound; were it cleaner or lighter it would still be a potato. But if it lacked whatever makes a potato a potato, it would obviously not be one.