Brian Eno says that ambient music - at least the incarnation of which he is credited as "inventing" - came about entirely by accident.
The story goes that he was recovering from a car accident in hospital and unable to move. A friend, thinking they were helping, put on some 18th century harp music but it was too quiet.
Unable to turn it up he was, at first, frustrated but then taken by the way the half-heard melodies blended with the sounds of the environment he was in.
I usually use some form of ambient music to lull me to sleep at night, often one of Eno's albums. And as I lay in bed last night, waiting for sleep to claim me, the following poem formed which seemed to sum it up perfectly:
Rain falling -