"the loudest yelps for liberty"

Re: Samuel Johnson, this from the Times:

Slavery repelled him. He took a freed slave, Francis Barber, into his house, and bequeathed him the bulk of his estate. His opinion of Americans ("I am willing to love all mankind," he confessed, "except an American") stemmed partly from the colonists' doublethink about freedom and slavery: "How is it that we hear the loudest yelps for liberty among the drivers of Negroes?"

From Mason & Dixon, p. 696:

The Driver's Whip is an evil thing, an expression of ill feeling worse than any between Master and Slave,- the contempt of the monger of perishable goods for his Merchandise,-- in its tatter'd braiding, darken'd to its Lash-Tips with the sweat and blood of Drove after Drove of human targets, the metal Wires work'd in to each Lash, its purpose purely to express hate with, and Hate's Corollary,-- to beg for the same denial of Mercy, should, one day, the roles be revers'd. Gambling that they may not be, Or, that they may."