… is from page 421 of volume 2 of The Collected Works of Armen A. Alchian  (2006); specifically, it’s from Alchian ‘s December 1958 review, in the Journal of the American Statistical Association, of Gary Becker ‘s 1957 book, The Economics of Discrimination :
When discrimination occurs, the discriminator must in fact either pay or forfeit income. This simple, but powerful, way of looking at the matter gets at the essence of prejudice and discrimination.
The above reality describes the effects of free markets. But (as explained by Becker, Alchian, Bob Higgs , Walter Williams , Jenny Roback-Morse , and other economists) when government imposes price controls – such as minimum wages – government effectively eliminates or greatly reduces the costs that are borne directly by individuals who indulge their prejudices and bigotries. The result is more unjustified and wasteful discrimination.