"The terror with which twins are regarded in the Niger Delta is exceedingly strange and real ..." Mary Kingsley continues, and it was the desire to fathom some of these bizarre emotions about twinning and twinship, many of which are reproduced - if less savagely - in our culture, that prompted Penelope Farmer, a twin bereaved of her other half, to compile this book. And as the extracts heap up, words as strong as "terror" become amply justified. The strength of feeling - curiosity, wonder and delight, on one side of the equation, disgust, resentment, even horror on the other - is everywhere palpable but never quite explicable. People just can't quite say what is so strange about twins.
It's an enviable state, to outsiders (and everyone else, even the mother, is to some extent an outsider). A twin I know once told me that she didn't understand loneliness. She had never felt it, because even if they weren't together, she knew her twin was in the world. But - and there is always an opposite, with this subject - later relationships can fail to match up, as one contributor says: "There is one problem ... in our adult lives we [twins] expect of our friends and partners what we receive from each other, a relationship that is more profound than between parents and children, most siblings and many couples."
Farmer launches herself autobiographically into the fray, prefacing each themed section of extracts with a mini-essay that is part factual digest and part reminiscence or personal exploration. She draws her material from the Classical era to the present day; prose and poetry, fiction and reportage, fact and fantasy. She takes a wide cultural view, with pieces about Bali, China, France, Germany and elsewhere, and extends her range to "Shadows, Reflections and Other Doubles" as well as alter egos, twin myths and mirrors.
Sometimes her thematic divisions prove confusing - any comment on twins seems to link to so many others that its placement in one section or another becomes arbitrary. For instance, a report on twins born in Bali in the 1930s, an event so distressing to the community that they tore down the birthplace and banished the "unclean" mother and babies, seems logically to belong with the Niger Delta report quoted earlier. But in fact the Bali story appears in a section entitled "Twins as Loved and Lovers", linked to other items on twin incest because the Balinese villagers thought the baby boy and girl were "wrong" to have shared the intimacy of the womb.
Similarly, when Farmer sets out to find passages about twins' sense of intimacy and oneness, she seems most able to prove this by its absence - that is, by loss. Perhaps only the peculiar pain of the separating of the doubled self can bring home to us just how forceful that doubling is. So in "The Nature of Twinship" comes this magnificently strange quote from Mark Twain, no less moving for its jokey style: "My twin and I got mixed up in the bathtub when we were only two weeks old and one of us was drowned, but we don't know which. Some think it was Bill and some think it was me."
Some of the most poignant and mysterious extracts are to do with the death of a twin. Shakespeare's heart-searing lines are well known - "I to the world am like a drop of water / that in the ocean seeks another drop" - and they really encapsulate any bereavement, any loneliness. But beside the agonies of grief, others talk of feelings of relief, of liberation, even of triumph over the dead twin. Just as non-twins are fascinated by doubles, so twins are interesting in being unique. Ise-Margaret Vogel remembers her pride at her father telling her, on the death of her sister: "You are the only one now ." One of the famous "Silent Twins", Jennifer, died on the day the two were released from Broadmoor: "When she died," June told Marjorie Wallace, "I came into my own. She let go of me and I got my life back."
Through quotes like these, as well as through her own contributions, Farmer brings across the harsher realities of twinship: the fights, the competitiveness and resentment, the guilts and jealousies. And she doesn't shirk the freak-show side of things: the Dionne Quints, the Kray twins, and a strong showing of Siamese twins - including a description by Donald Newlove of a young girl having sex with a Siamese pair which verges on pap porn.
Such extracts bring up the question of literary merit in this collection. Despite the scores of great writers, from Stevenson to Tacitus, Shakespeare to Angela Carter, we have to put up with too many duds, whose poor writing was presumably included only for its subject matter. And there are too many repeats: quoting the same source twice or more within a single section is surely to break the unwritten rules of the anthologer's art.
There are other facets, too, of this perpetually intriguing subject that Farmer could have covered more thoroughly. The way in which twins divide the world between them, for instance - if one is good at music, the other will often avoid that and concentrate on sport, say. My twin daughter cannot see why she needs to learn spellings, since she knows her brother knows them; at eight she still regards his mind as an extension of her own. And the siblings of twins, always looking in from outside, might have found a voice - as indeed might the parents. "All of us twins are freaks," Farmer writes, but in fact it is not a rare state. It is, however, one so fascinating that a book such as this could multiply its length endlessly, and she has provided a rich selection for insiders and outsiders alike.