|That's classical political economy though. If you want to look at racism after the classicals, Jevons isn't a bad place to start:
"Questions of this kind [work effort] depend greatly upon the character of the race. Persons of an energetic disposition feel labour less painfully than their fellow-men, and, if they happen to be endowed with various and acute sensibilities, their desire of further acquisition never ceases. A man of lower race, a negro for instance, enjoys possession less, and loathes labour more; his exertions, therefore soon stop. A poor savage would be content to gather the almost gratuitous fruits of nature, if they were sufficient to give sustenance; it is only physical want which drives him to exertion." Theory of political economy, 1871, p. 182-83.