Just to pluck one example out of thousands I could adduce: I went through two and a half decades of a passion for Western history, five years of that at a major university wherein (aside from my assigned readings from various classes, in addition to copious reading on my own) I had many personal discussions with history professors -- and not once during that time did I learn that the great Spanish writer Cervantes, known for the perennial classic Don Quixote, had himself been a prisoner of Muslims in North Africa, and had been enslaved by Muslims.
As we should know, but don't: Muslims routinely abducted Westerners and enslaved them, for centuries -- documented in the books White Gold by Giles Miton, as well as Christian Slaves, Muslim Masters: White Slavery in the Mediterranean, the Barbary Coast and Italy, 1500-1800, by Robert C. Davis, whose author estimates approximately one million or more Westerners who suffered this cruel fate at the hands of Muslims during that time period alone (see also Chapter One -- available to read for a free preview at Amazon.com -- of Peter Hammond's new book, Slavery, Terrorism & Islam, for a good overview of Islamic slavery). And, of course, a good deal of the cruel problem of the so-called "Barbary pirates" (i.e., Muslims adapted to water travel) entailed their abduction and enslavement of innumerable Europeans, and then, fatefully, of Americans.
Nor did I once learn that Cervantes spent most of his life (after he was luckily ransomed free from his Muslim dungeon) writing plays about how evil and dangerous Islam is. That, in fact, became his true passion, not so much the novel for which he is famous. But one would never learn this important fact by majoring in Western history at a major Western university in the latter half of the 20th century! I only found out about it almost by chance one day, when I decided to Google "Cervantes" and "Islam" and spent over an hour scrolling through pages and pages of links, before I found an obscure, dusty old tome titled Michel de Cervantes, sa vie, son temps, son oeuvre politique et littéraire ("Miguel de Cervantes: His life, his time, his political and literary works"), by some 19th century French historian, Émile Chasles.
The book is likely not available even in most university libraries, and had someone not seen fit to scan it and upload it onto Google Books, I may never have discovered it. Also, it's not translated into English, which further limits its audience. It should be on the syllabus of required (or at least recommended) reading for every course in Western history -- certainly every course dealing with the history of the literature classics; for Cervantes was the Spanish equivalent of Shakespeare for England, or Dante for Italy. And would it be presumptuous to suggest that it also should be used by at least a few professors here and there as a teaching point in the history of Islam and the West? Shame on the West for letting such an important study lie largely ignored among the trillions of interstices of the Internet, where it will be found only by sheer and exceedingly seldom accident!
Well, not if old Hesperado can help it, by gum! Now that I've published this essay on Chasles here, we can safely say that three more people know about him!
All seriousness aside (as Steve Allen used to say), I do promise the reader -- and myself -- that in the near future I will publish translations and commentary on some of the more apposite extracts from this invaluable study by Chasles.