At a few minutes past five o'clock in the afternoon of 7 May 1959, a bulky, shambling figure approached the lectern at the western end of the Senate House in Cambridge. In the body of the ornately plastered neoclassical building sat a large gathering of dons and students, together with a number of distinguished guests, who had assembled for one of Cambridge's show-piece public occasions, the annual Rede lecture. The figure who was about to address them was C.P. Snow (then more formally styled Sir Charles, soon to be Lord Snow, but known throughout the world by his initials). Snow had been a research scientist; he had high-level administrative experience in the Civil Service and in private industry; he was a successful novelist and prominent reviewer; and he had now achieved the indefinable status of a ‘public figure’, licensed to announce his opinions on all manner of topics. By the time he sat down over an hour later, Snow had done at least three things: he had launched a phrase, perhaps even a concept, on an unstoppably successful international career; he had formulated a question (or, as it turned out, several questions) which any reflective observer of modern societies needs to address; and he had started a controversy which was to be remarkable for its scope, its duration, and, at least at times, its intensity.

The title of Snow's lecture was ‘The Two Cultures and the Scientific Revolution’.