As 1665 drew to a close, many people were anxious about the following year, which would be burdened with the digits 666, the ominous Number of the Beast. Even though London was indeed devastated by the Great Fire in 1666, John Dryden chose to celebrate the year with his poem ‘Annus Mirabilis’. Thanks to God’s intervention, he wrote, the year had proved less disastrous than it might have done, especially because, in July, the English fleet won a great victory against the Dutch (the naval advantage was reversed in 1667). For scientists, 1666 is better known as the annus mirabilis of Isaac Newton, the year in which he retreated to his country cottage and (supposedly) not only discovered gravity beneath an apple tree, but also formulated calculus and proved that colours exist within sunlight. Philip Larkin identified the most wonderful year of all in his own poem carrying the title ‘Annus Mirabilis’:

Sexual intercourse began
In nineteen sixty-three
(Which was rather late for me) –
Between the end of the Chatterley ban
And the Beatles’ first LP.

Establishing precise dates makes the past conveniently tidy. Historians with a methodical frame of mind can impose apparent order on chaotic streams of shifting events, enabling them to create appealingly neat stories about individual inspiration, planned innovation and progress towards an ever-better future. In the very first sentence of The