(Bo-o'-tees ), or the ox-driver, a constellation. According to ancient mythology, Boötes invented the plough, to which he yoked two oxen, and at death, being taken to heaven with his plough and oxen, was made a constellation. Homer calls it “the wagoner.”
Wide o'er the spacious regions of the north, That see Boötes urge his tardy wain.
Thomson: Winter, 834-5.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894