On September 14, 1741, George Frideric Handel finished writing Messiah. He had begun on August 22 and had worked almost without stopping for 24 days, in a state his servant described by saying he had barely left the room and that his food had often gone untouched. He was 56.
The speed is unusual but not inexplicable. Handel had been composing Italian operas for decades, mostly to deadline, and he reused material in a way that was normal in the eighteenth century and would be considered theft now: several choruses in Messiah are reworkings of his own Italian duets, and some passages come from other composers. What is not borrowed is the pacing of the whole. Messiah is in three parts, the birth, the passion and the resurrection, and it is built so that the choruses carry the argument and the arias comment on it, which is the opposite of how he wrote opera.
The text was assembled by Charles Jennens, a friend and a wealthy landowner with an interest in theology, who cut and arranged passages almost entirely from the King James Bible and the Book of Common Prayer. There is no plot and no named character; nobody in the work says anything as themselves. Jennens and Handel later fell out over the setting, with Jennens complaining that the music did not match the dignity of the words.
It was not for London. Handel had been invited to Dublin by the Duke of Devonshire, then Lord Lieutenant of Ireland, and the first performance was on April 13, 1742, at the New Music Hall in Fishamble Street, as a benefit for three charities including a debtors' prison. It was oversubscribed; the newspapers asked ladies not to wear hooped skirts so that more people could fit. It was a success.
In London it was not, at first. The 1743 performances drew criticism for putting scripture on a stage, and Handel had to move from theatre to theatre. It became a fixture through the annual charity performances for the Foundling Hospital, which he began in 1750 and which continued after his death.
The Hallelujah chorus tradition, the audience standing, is usually traced to George II at the 1743 London premiere, and there is no contemporary evidence for it. Handel is reported to have said of the Hallelujah that he did think he saw all Heaven before him, and the great God himself. He died in 1759 and is buried in Westminster Abbey.