Looking at an essay about Hume and slavery, I came across this quote.

I am apt to suspect the negroes and in general all other species of men (for there are four orfive different kinds) to be naturally inferior to the whites. There never was a civilized nationof any other complexion than white, nor even any individual eminent either in action orspeculation. No ingenious manufactures amongst them, no arts, no sciences…. [T]here areNEGROE slaves dispersed all over EUROPE, of which none ever discovered any symptomsof ingenuity; tho' low people, without education, will start up amongst us, and distinguishthemselves in every profession. In JAMAICA, indeed, they talk of one negroe as a man of parts and learning; but 'tis likely he is admired for very slender accomplishments, like a parrot, who speaks a few words plainly.

[According to the essay] (http://www.academia.edu/890401/Making_excuses_for_Hume_slavery_racism_and_a_reassessment_of_David_Hume_s_thoughts_on_personal_liberty), it is from a footnote in a revised edition (1753) of 'Of National Characters'.

I'm wondering about why Hume, a historian, presumably well-read, would discard a number of non-white civilizations, in particular the Islamic Golden Age. (Others that come to mind, the Ottoman Empire and Edo period Japan.)

Also a sub-question (which is probably bigger and better than the title): how was the Rashidun Caliphate regarded by scientists and scholars of the Enlightenment?