‘Nothing is as beautiful as those trains we missed,’ wrote the Symbolist poet Jules Laforgue; and how especially golden seem geniuses who die young. Should it mitigate or enhance our regret that many of Frank Ramsey’s extraordinarily innovative ideas only came to be understood long after he died, aged twenty-six, in 1930? Straddling philosophy, maths, logic, probability theory and economics, the papers he wrote in the space of a few years anticipated John von Neumann’s game theory, developments in subjective probability and optimal taxation, and gave us the Ramsey sentence, the Ramsey test for conditionals, Ramsey’s theorem, Ramsification, the Ramsey tax rule, Ramseyan humility, the Ramsey-Cass-Koopmans model, and more. Aged eighteen, he translated Wittgenstein’s Tractatus Logico-Philosophicus into English and introduced it to the Vienna Circle; in turn, he influenced Wittgenstein’s move from his early to his later thought. John Maynard Keynes constantly consulted him over the maths and statistics in his own work. It’s tantalising to think what might have come of a meeting between Ramsey and the computer scientist Alan Turing, who arrived at Cambridge, where Ramsey had been teaching, a year after his death.