Which composer wrote the Goldberg Variations?

Bach, published in 1741 - an aria and thirty variations built not on the tune but on the bass line beneath it, which is why they can wander so far and still feel anchored.

The structure is severe and hidden. Every third variation is a canon, and the interval widens by one step each time: the third is a canon at the unison, the sixth at the second, and so on up to the ninth at the ninth. The last is not a canon at all but a quodlibet stacking two popular songs of the day on top of the bass, which appears to be a family joke.

The story that they were written to soothe an insomniac count, played through the night by his harpsichordist Goldberg, comes from a biography published fifty years later and is probably not true - Goldberg was about fourteen. Their modern life dates from Glenn Gould's 1955 recording, which took them at a speed nobody expected on an instrument Bach never wrote for; Gould re-recorded them, much slower, shortly before he died.