Once upon a time, in a western land, there were no black swans. Such an understanding about the world formed the basis of commentary such as that of 2nd century Roman poet Juvenal in his Satire VI , writing about a good wife: Rara avis in terris nigroque simillima cygno , “A rare bird on this earth, like nothing so much as a black swan”. At the time, black swans were believed not to exist, since all records of swans documented them as having white feathers. The expression “black swan” – in Latin, several European languages, and in English from the 16th century, based on the classical Latin niger cygnus – thus referred to something impossible, non-existent, which defied belief. (Also borrowed into English was rara avis “rare bird”, also for that which is unusual, exceptional or rarely encountered.) References from the 16th to 18th centuries can be found to “husbands without faults (if such black swans there be)”, or “an honest lawyer”. All this changed in the 17th century, when Dutch explorers, encountering the Western Australian coast, discovered that the then-mythical black swan existed. Descriptions and, later, specimens of Cygnus atratus – native to Australia, and an important totem for many Aboriginal communities, featuring in songs and constellations – upended Europeans’ beliefs. “Black swan” evolved to refer to the idea that a perceived impossibility might later be disproven; Austrian-British philosopher Karl Popper used the parable of the black swan in 1959 to illustrate the power of falsification in science. The new millennium saw the metaphor extended, initially for financial markets, by Lebanese-American mathematical statistician Nassim Nicholas Taleb, and to major scientific discoveries, historical events and artistic accomplishments. Black swan events lie outside the realm of expectations, have an extreme impact, but are considered retrospectively as explicable, predictable. The black swan metaphor has been applied to the Covid-19 pandemic and Russia’s invasion of Ukraine – but scientists and political analysts beg to differ. Indeed, such linguistic labelling serves to reject accountability, and encourage fatalism and wilful ignorance. Enter – in a crash – the grey rhino. Huge, obvious and coming right at you, this metaphor, coined by American policy analyst Michele Wucker in 2013, underscores high-likelihood, high-impact risks that are noted but nonetheless neglected. (This differs from the elephant in the room that nobody talks about.) Acknowledging grey rhinos is an important first step in dealing with them.