> Who in 12th-century England would have seen an elephant or a crocodile? Tales filtered back from Crusaders and distant travellers of a giant herbivore with a nose so long and pliable that it could pick up men and seat them on its back, and of an armour-plated carnivore that lurked in water and could be mistaken by the unwary for a log of wood. These were as improbable – and therefore as possible – as a white horse with a long horn in the middle of its foreheadI wonder if there's anything similar today? Subatomic particles or astronomical objects? Mental health seems to be an area where we currently have no idea how things really work in the brain.