Britain feels broken. Broken by COVID-19. Broken by Brexit. Broken by the lies that have been dripped into British political debates these past 5 years. Those scientists and doctors who voted to remain in the European Union—perhaps based on a belief in the public value of research and clinical networks that have been painstakingly built over half a century between the UK and its European neighbours—were accused of Project Fear. But now that the UK has finally left the EU, with the thinnest of thin deals, one can look back and say that the arguments to leave were themselves based on nothing but fear—fear of European expansion, fear of the costs of EU membership, fear of immigration, fear of the Euro, and fear of the European Court of Justice. The British Prime Minister says that we should be celebrating an “amazing moment” in the history of our country. But living under an intensifying lockdown in response to a coronavirus epidemic that is manifestly out of control, many might not be able to comprehend that “amazing moment”. Instead, what they might feel is a profound melancholy for a country that has wounded itself, insulted its friends, and harmed a future generation that will bear the burden of their mistakes. In the late 18th century, Europe was also in turmoil. A Declaration of Independence was signed on July 4, 1776, announcing the separation of 13 American colonies from British rule. The measures that Americans took to free themselves from Britain passed like an electric shock through European nations. The French monarchy was presiding over unsustainable debt and unfair taxes. If the American people could overthrow a corrupt government, why not the French? Meanwhile, the Enlightenment was creating conditions for a raft of inventions and discoveries that challenged longstanding assumptions about the organisation of society. Amid this political and intellectual turbulence, in 1784 the German philosopher Immanuel Kant wrote a short essay with far-reaching implications—Idea for a Universal History with a Cosmopolitan Intent. He sought to show that despite the complicated and unpredictable nature of individuals, there might be a “guiding thread” that directs human progress. Kant set out nine theses to prove his case. First, our natural capacities develop completely and in conformity with their end—eg, an organ that is not intended to be used is a contradiction. Second, the full possibilities of human reason can never be fulfilled in one individual, but only for our entire species across “a perhaps incalculable sequence of generations”, each passing its knowledge to the next. Third, we have the gifts of reason and free will to produce everything from ourselves. Fourth, the means that nature uses to bring about the development of human capacities is antagonism—that is, our “unsocial sociability”, our need to live harmoniously among others but our equal need to fulfil our own individual desires and aspirations. Fifth, the greatest challenge we face in achieving the highest attainable development of our capacities is the creation of “a universal civil society”. Sixth, each of us needs an authority to set limits on our freedom. Seventh, “The problem of establishing a perfect civil constitution depends on the problem of law-governed external relations among nations.” Kant envisages a “federation of peoples”, a “cosmopolitan state in which the security of nations is publicly acknowledged.” Eighth, “One can regard the history of the human species...as the realisation of a hidden plan of nature to bring about [a] perfect national constitution, as the sole state in which all of humanity's natural capacities can be developed.” Nature's “supreme objective”, according to Kant, is “a universal cosmopolitan state.” And finally, although some might consider this “universal history of the world” impossibly romantic, the history of human progress does offer evidence that it might be true. Kant doesn't believe that history proceeds mechanically according to some predestined plan. But he does suggest that if the natural endpoint of human society is cosmopolitanism, it might prove to be “some small motivation” to national leaders as they reflect on their ambitions. At a moment of pandemic and political turmoil, Kant's notion of a “guiding thread” might indeed be comforting. Despite the current worldwide division and disorder, nations and peoples will reunite, polarisations will diminish, and a spirit of cooperation will be renewed.