Baa, Baa, Black Sheep is an English nursery rhyme. the earliest version of the nursery rhyme dates back to 1731. In the 20th century, there has been some discussion on the nursery rhyme and debates to explain the meaning including taxes on wool and the slave trade. The words have changed little in two and a half centuries.
Baa, baa, black sheep,
Have you any wool?
Yes, sir, yes, sir,
Three bags full;
One for the master,
And one for the dame,
And one for the little boy
Who lives down the lane.
Source: http://en.wikipedia.org/