This week we launch our new illustrated souvenir guide to Wellcome Collection, A Guide for the Incurably Curious. Its author Marek Kohn reflects on some mysterious glimpses into medical history.Keen to renew the acquaintance of former colleagues, I leapt at the chance to write the text for Wellcome Collection’s Guide. The people who worked on Wellcome’s medical history galleries at the Science Museum have long since dispersed, but the objects are still around. When I first walked into Medicine Man, Wellcome Collection’s subtle cabinet of curiosities, it felt like walking into a reception full of faces that I hadn’t seen for a lot longer than I’d care to count. I almost felt like saying hello to several of them.However long the interval, those aren’t faces one forgets. And they really were like colleagues in several important respects. They sat around in the workroom, they were full of stories and they took part in conversations. It’s nice to see how they have prospered since. You could even say that they are enjoying celebrity. The main thing, though, is that they enjoy order and recognition, the basic conditions of a healthy existence for a collected object.Yet many of them still aren’t recognised for what they are, because although the objects in the collection – well over 100,000 of them – are now catalogued and sorted, they arrived free from provenance, and they therefore remain mysteries. One of the most compelling sensations the collection produces is that you could never get to the end of it; there will always be something that has yet to be unpacked and revealed. A similar sensation attaches to some of the individual objects themselves; no matter how much research you did, you would never be quite sure whether they were really one thing or another.The feeling of being suspended between two (or more) elusive possibilities is particularly heady around some of the more eye-catching items featured in Medicine Man and the Guide. Is the velvet-lined chastity belt a medieval invention or a 19th-century fantasy of medieval sexual control? Is the ornately decorated chair made of blades a practical torture instrument or some kind of display piece constructed to signal the idea of torture? Who used it? How, why, and upon whom? Questions like these, their facets glinting with possibilities, are what makes curiosity incurable.They’re certainly among the most challenging ones that arise when you’re trying to thumbnail the picture in a brief caption. But although you may not get the answers you want, you see half a dozen new questions for each unanswered one, and pathways to follow in pursuit of them. These defiantly enigmatic objects may speak volumes even though they evade the question you originally asked. In other words, they behave very like the artworks next door in Medicine Now, but through circumstance rather than design.Henry Wellcome’s ‘Tabloid’ pharmaceutical brand was intended to signify quality in compressed form. That was a basic requirement for the Guide, too – which also made it a chance to be leapt at, as there are few activities more rewarding for writers than the compression of possibilities. A glimpse can be more of a revelation than a teeming scene.Marek Kohn is the author of ‘Dope Girls’ and ‘Turned Out Nice: How the British Isles Will Change as the World Heats Up’. You can follow him on twitter at @marekkohn. A Guide for the Incurably Curious is priced £5 and can be bought online via Blackwell’s.