He poses to the reader to identify the period in which this vile antisemitc passage which appears below was written, its a challenge not without some consequence.
Our people [the Muslims] observing thus the occupations of the Jews and the Christians concluded that the religion of the Jews must compare unfavorably as do their professions, and that their unbelief must be the foulest of all, since they are the filthiest of all nations. Why the Christians, ugly as they are, are physically less repulsive than the Jews may be explained by the fact that the Jews, by not intermarrying, have intensified the offensiveness of their features. Exotic elements have not mingled with them; neither have males of alien races had intercourse with their women, nor have their men cohabited with females of a foreign stock. The Jewish race therefore has been denied high mental qualities, sound physique, and superior lactation. The same results obtain when horses, camels, donkeys, and pigeons are inbred.
After reading this passage, do try to date the period in which this rather vile writing appeared, you may be in for a surprise.
Make sure you read his full article Here.
Andrew G. Boston: The Legacy of Islamic Antisemitism