He lived in the same room for twenty-seven years and never let anyone in. After he died they went in, and found among the rubbish several works everyone had assumed were lost.
Satie was born in 1866 in Honfleur, Normandy. He entered the Paris Conservatoire at thirteen, and his reports got blunter each year: "gifted but indolent" the first year, "the laziest student in the Conservatoire" the next. He was expelled in 1882. He later described the building as "a vast, very uncomfortable, and rather ugly building; a sort of district prison."
In his early twenties he played piano at the Chat Noir in Montmartre, a cabaret famous for its nonsense. The Gymnopédies come from those years, and on the scores he gave himself a title that was not "composer" but "gymnopédiste" — a word he made up.
At thirty-nine he did something very few people do: he went back to school. In 1905 he enrolled at the Schola Cantorum and started again from counterpoint, staying until 1912. This time the reports said he was conscientious, and good.
From 1898 he lived in Arcueil, eight kilometres south of Paris, in one room, until his death in 1925 — twenty-seven years in which no visitor was ever admitted. His friends opened that door for the first time after he died, and found among the accumulated rubbish several works that had been assumed lost.
Late in life he proposed something he called furniture music: music written not to be listened to, meant to sit in the room like a chair or a lamp. It was taken as a joke at the time. Eighty years later it turned out to be the source of an entire genre.
Satie's music has few notes in it, and it is never in a hurry. The same accompanying figure will turn over and over until you stop noticing it — that is not laziness, that is the effect he wanted.
He liked harmonies that sound as though they have no intention of resolving: a chord hangs there, the next step is obvious, and he simply does not take it, letting it dissolve instead. That is why his music often feels neither sad nor happy, just present.
One more giveaway: the bass is steady and slow, and the melody above sounds like something added afterwards, almost as an afterthought.