According to James Ussher, Church of Ireland Archbishop of Armagh (1581-1656):
the world was created at approximately six o'clock in the evening on October 22nd, 4004 BC.
Ussher worked this out from the bible, of course - well, not from the old Greek version called the Septuagint (people tend to live a lot longer in that one) but from the Hebrew bible.
It's quite an easy calculation to make as far as the oldest part of the story goes because the Bible tells us who everyone's dad is, and how long people everyone lived (though the date of the birth of Abraham is still hotly disputed). After that there are gaps in the record, so Ussher had to work the chronology out using externally verifiable dates (importantly, the date of the death of King Nebuchadnezzar).
Once Ussher had done all the reading and thinking and sums the answer came out as about 4000 BC. Unfortunately that doesn't quite work because that means that then Jesus Christ wouldn't have been born until after Herod died, so in the end the date 4004BC for the creation of the world was the best Ussher could do (he decided to believe Matthew and not Luke about the date of Jesus' birth (it's jolly tricky to believe both of them)).
Ussher deduced the time of year for the creation from the fact that the Autumn Equinox is the date of the Jewish New Year, and the creation must have been begun on a Sunday because the seventh day, the day of rest, must have been the Sabbath. The time of day was indicated by a reference to the evening and the fact that in many ancient (and modern) calendars, the day starts at dusk.
But what sort of a man devotes so much time and ingenuity to a piece of literary criticism?
Well, a man who lived in dangerous and confusing times, that's who. Ussher was a puritan, a monarchist, and an Irishman with an instinct for conciliation who was living through a very bloody Civil War. (He was also a historian with a natural reluctance to dismiss stories for want of hard proof, as he showed in his history of Christianity in Britain, Britannicarum ecclesiarum antiquitates, where he devoted a whole chapter to the entirely fictional adventures of the entirely fictional King Lucius.)
I can see why poor Bishop Ussher might have been glad to retreat to his study to work out the date of the creation of the world.
And I'm not entirely sure why, but it's also rather a source of comfort, in some strange way I don't really understand, that he did.
Word To Use Today: creation. This word come from the Latin word creāre, to produce or make.