The blues were around long before African Americans put them to music.
The expression originates in the belief of early English settlers that “blue devils,” or mean spirits, had followed them to their new land.
These devils were thought to be the cause of sadness, and so a bout of depression was called “the blues.”
Because no one could have been sadder than the black slaves, their raw expression of the mood in a unique and brilliant musical form became known as “the blues.”