Interesting to me that the tendency is to skip from millenia old history to the modern era, leaving out the period from 300 A.D. to the Renaissance . . . or whatever they regarded as modern then. I think we have lost a lot of lessons from that gap in historical focus. One of the lessons is the danger of Islam.
You have to understand that the 18th century took a more systematic view of education, at least at this aristocratic level, so that one learns the foundations - and for the Anglo-American philosophes that was primarily the ancient classics before tackling the practical and the modern at university and beyond. A gentleman's education did not end with university, but rather continued with private reading. Much of modern history, Voltaire, Gibbon, Hume, etc. (recall they were all best known first as historians) was being published and was the sort of thing that gentlemen read in their leisure, rather than what students learned in school.